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Computer Science Illuminated Revised Nell B. Dale
Digital Instant Download
Author(s): Nell B. Dale; John Lewis
ISBN(s): 9781284055917, 1284055914
Edition: Paperback
File Details: PDF, 13.57 MB
Year: 2014
Language: english

2

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Publisher: Cathy L. Esperti
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Library of Congress Cataloging-in-Publication Data
Dale, Nell.
Computer science illuminated / Nell Dale, PhD, University of Texas-Austin, Department of Computer Science,
John A. Lewis, Virginia Tech. — Sixth edition.
pages cm
Includes bibliographical references and index.
ISBN 978-1-284-05591-7 (pbk.) 1. Computer science. I. Lewis, John, 1963- II. Title.
3

QA76.D285 2015
004—dc23
2014032093
6048
Printed in the United States of America
19 18 17 16 15 10 9 8 7 6 5 4 3 2 1
4

To my wife, Sharon, and our children, Justin, Kayla, Nathan, and
Samantha.
—John Lewis
To all the students who will use this book: It is written for you.
—Nell Dale
5

John Lewis, Virginia Tech
John Lewis is a leading educator and author in the field of computer science. He has
written a market-leading textbook on Java software and program design. After earning his
PhD in Computer Science, John spent 14 years at Villanova University in Pennsylvania.
He now teaches computing at Virginia Tech, his alma mater, and works on textbook
projects out of his home. He has received numerous teaching awards, including the
University Award for Teaching Excellence and the Goff Award for Outstanding Teaching.
His professional interests include object-oriented technologies, multimedia, and software
engineering. In addition to teaching and writing, John actively participates in the ACM
Special Interest Group on Computer Science Education (SIGCSE) and finds time to spend
with his family and in his workshop.
Nell Dale, The University of Texas at Austin
Well-respected in the field of computer science education, Nell Dale has served on the
faculty of The University of Texas at Austin, for more than 25 years and has authored over
40 undergraduate Computer Science textbooks. After receiving her BS in Mathematics and
Psychology from the University of Houston, Nell entered The University of Texas at
Austin, where she earned her MA in Mathematics and her PhD in Computer Science. Nell
has made significant contributions to her discipline through her writing, research, and
service. Nell’s contributions were recognized in 1996 with the ACM SIGCSE Award for
Outstanding Contributions in Computer Science Education and in 2001 with the ACM
Karl V. Karlstrom Outstanding Educator Award. She was elected an ACM Fellow in 2010.
In 2013, she received the IEEE Taylor L. Booth Education Award. Nell has retired from
full-time teaching, giving her more time to write, travel, and play tennis and bridge. She
currently resides in Austin, Texas.
6

BRIEF CONTENTS
1 Laying the Groundwork Laying the Groundwork
Chapter 1 The Big Picture
2 The Information Layer
Chapter 2 Binary Values and Number Systems
Chapter 3 Data Representation
3 The Hardware Layer
Chapter 4 Gates and Circuits
Chapter 5 Computing Components
4 The Programming Layer
Chapter 6 Low-Level Programming Languages and Pseudocode
Chapter 7 Problem Solving and Algorithms
Chapter 8 Abstract Data Types and Subprograms
Chapter 9 Object-Oriented Design and High-Level Programming Languages
5 The Operating Systems Layer
Chapter 10 Operating Systems
Chapter 11 File Systems and Directories
6 The Applications Layer
Chapter 12 Information Systems
Chapter 13 Artificial Intelligence
Chapter 14 Simulation, Graphics, Gaming, and Other Applications
7 The Communications Layer
Chapter 15 Networks
Chapter 16 The World Wide Web
Chapter 17 Computer Security
8 In Conclusion
Chapter 18 Limitations of Computing
7

CONTENTS
1 Laying the Groundwork
Chapter 1 The Big Picture
1.1 Computing Systems
Layers of a Computing System
Abstraction
1.2 The History of Computing
A Brief History of Computing Hardware
A Brief History of Computing Software
Predictions
1.3 Computing as a Tool and a Discipline
Summary
Ethical Issues: Digital Divide
Key Terms
Exercises
Thought Questions
2 The Information Layer
Chapter 2 Binary Values and Number Systems
2.1 Numbers and Computing
2.2 Positional Notation
Binary, Octal, and Hexadecimal
Arithmetic in Other Bases
Power-of-2 Number Systems
Converting from Base 10 to Other Bases
Binary Values and Computers
Summary
Ethical Issues: The FISA Court
Key Terms
Exercises
Thought Questions
Chapter 3 Data Representation
3.1 Data and Computers
8

Analog and Digital Data
Binary Representations
3.2 Representing Numeric Data
Representing Negative Values
Representing Real Numbers
3.3 Representing Text
The ASCII Character Set
The Unicode Character Set
Text Compression
3.4 Representing Audio Data
Audio Formats
The MP3 Audio Format
3.5 Representing Images and Graphics
Representing Color
Digitized Images and Graphics
Vector Representation of Graphics
3.6 Representing Video
Video Codecs
Summary
Ethical Issues: The Fallout from Snowden’s Revelations
Key Terms
Exercises
Thought Questions
3 The Hardware Layer
Chapter 4 Gates and Circuits
4.1 Computers and Electricity
4.2 Gates
NOT Gate
AND Gate
OR Gate
XOR Gate
NAND and NOR Gates
Review of Gate Processing
Gates with More Inputs
4.3 Constructing Gates
Transistors
4.4 Circuits
Combinational Circuits
9

Adders
Multiplexers
4.5 Circuits as Memory
4.6 Integrated Circuits
4.7 CPU Chips
Summary
Ethical Issues: Codes of Ethics
Key Terms
Exercises
Thought Questions
Chapter 5 Computing Components
5.1 Individual Computer Components
5.2 The Stored-Program Concept
von Neumann Architecture
The Fetch–Execute Cycle
RAM and ROM
Secondary Storage Devices
Touch Screens
5.3 Embedded Systems
5.4 Parallel Architectures
Parallel Computing
Classes of Parallel Hardware
Summary
Ethical Issues: Is Privacy a Thing of the Past?
Key Terms
Exercises
Thought Questions
4 The Programming Layer
Chapter 6 Low-Level Programming Languages and Pseudocode
6.1 Computer Operations
6.2 Machine Language
Pep/8: A Virtual Computer
6.3 A Program Example
Hand Simulation
Pep/8 Simulator
6.4 Assembly Language
Pep/8 Assembly Language
10

Assembler Directives
Assembly-Language Version of Program Hello
A New Program
A Program with Branching
A Program with a Loop
6.5 Expressing Algorithms
Pseudocode Functionality
Following a Pseudocode Algorithm
Writing a Pseudocode Algorithm
Translating a Pseudocode Algorithm
6.6 Testing
Summary
Ethical Issues: Software Piracy
Key Terms
Exercises
Thought Questions
Chapter 7 Problem Solving and Algorithms
7.1 How to Solve Problems
Ask Questions
Look for Familiar Things
Divide and Conquer
Algorithms
Computer Problem-Solving Process
Summary of Methodology
Testing the Algorithm
7.2 Algorithms with Simple Variables
An Algorithm with Selection
Algorithms with Repetition
7.3 Composite Variables
Arrays
Records
7.4 Searching Algorithms
Sequential Search
Sequential Search in a Sorted Array
Binary Search
7.5 Sorting
Selection Sort
Bubble Sort
Insertion Sort
7.6 Recursive Algorithms
11

Subprogram Statements
Recursive Factorial
Recursive Binary Search
Quicksort
7.7 Important Threads
Information Hiding
Abstraction
Naming Things
Testing
Summary
Ethical Issues: Open-Source Software
Key Terms
Exercises
Thought Questions
Chapter 8 Abstract Data Types and Subprograms
8.1 What Is an Abstract Data Type?
8.2 Stacks
8.3 Queues
8.4 Lists
8.5 Trees
Binary Trees
Binary Search Trees
Other Operations
8.6 Graphs
Creating a Graph
Graph Algorithms
8.7 Subprograms
Parameter Passing
Value and Reference Parameters
Summary
Ethical Issues: Workplace Monitoring
Key Terms
Exercises
Thought Questions
Chapter 9 Object-Oriented Design and High-Level Programming Languages
9.1 Object-Oriented Methodology
Object Orientation
Design Methodology
12

Example
9.2 Translation Process
Compilers
Interpreters
9.3 Programming Language Paradigms
Imperative Paradigm
Declarative Paradigm
9.4 Functionality in High-Level Languages
Boolean Expressions
Data Typing
Input/Output Structures
Control Structures
9.5 Functionality of Object-Oriented Languages
Encapsulation
Classes
Inheritance
Polymorphism
9.6 Comparison of Procedural and Object-Oriented Designs
Summary
Ethical Issues: Hoaxes and Scams
Key Terms
Exercises
Thought Questions
5 The Operating Systems Layer
Chapter 10 Operating Systems
10.1 Roles of an Operating System
Memory, Process, and CPU Management
Batch Processing
Timesharing
Other OS Factors
10.2 Memory Management
Single Contiguous Memory Management
Partition Memory Management
Paged Memory Management
10.3 Process Management
The Process States
The Process Control Block
10.4 CPU Scheduling
13

First Come, First Served
Shortest Job Next
Round Robin
Summary
Ethical Issues: Medical Privacy: HIPAA
Key Terms
Exercises
Thought Questions
Chapter 11 File Systems and Directories
11.1 File Systems
Text and Binary Files
File Types
File Operations
File Access
File Protection
11.2 Directories
Directory Trees
Path Names
11.3 Disk Scheduling
First-Come, First-Served Disk Scheduling
Shortest-Seek-Time-First Disk Scheduling
SCAN Disk Scheduling
Summary
Ethical Issues: Privacy: Opt-In or Opt-Out?
Key Terms
Exercises
Thought Questions
6 The Applications Layer
Chapter 12 Information Systems
12.1 Managing Information
12.2 Spreadsheets
Spreadsheet Formulas
Circular References
Spreadsheet Analysis
12.3 Database Management Systems
The Relational Model
Relationships
Structured Query Language
14

Database Design
12.4 E-Commerce
Summary
Ethical Issues: Politics and the Internet: The Candidate’s View
Key Terms
Exercises
Thought Questions
Chapter 13 Artificial Intelligence
13.1 Thinking Machines
The Turing Test
Aspects of AI
13.2 Knowledge Representation
Semantic Networks
Search Trees
13.3 Expert Systems
13.4 Neural Networks
Biological Neural Networks
Artificial Neural Networks
13.5 Natural Language Processing
Voice Synthesis
Voice Recognition
Natural Language Comprehension
13.6 Robotics
The Sense–Plan–Act Paradigm
Subsumption Architecture
Physical Components
Summary
Ethical Issues: Initial Public Offerings
Key Terms
Exercises
Thought Questions
Chapter 14 Simulation, Graphics, Gaming, and Other Applications
14.1 What Is Simulation?
Complex Systems
Models
Constructing Models
14.2 Specific Models
Queuing Systems
15

Meteorological Models
Computational Biology
Other Models
Computing Power Necessary
14.3 Computer Graphics
How Light Works
Object Shape Matters
Simulating Light
Modeling Complex Objects
Getting Things to Move
14.4 Gaming
History of Gaming
Creating the Virtual World
Game Design and Development
Game Programming
Summary
Ethical Issues: Gaming as an Addiction
Key Terms
Exercises
Thought Questions
7 The Communications Layer
Chapter 15 Networks
15.1 Networking
Types of Networks
Internet Connections
Packet Switching
15.2 Open Systems and Protocols
Open Systems
Network Protocols
TCP/IP
High-Level Protocols
MIME Types
Firewalls
15.3 Network Addresses
Domain Name System
Who Controls the Internet?
15.4 Cloud Computing
Summary
Ethical Issues: The Effects of Social Networking
Key Terms
16

Exercises
Thought Questions
Chapter 16 The World Wide Web
16.1 Spinning the Web
Search Engines
Instant Messaging
Weblogs
Cookies
Web Analytics
16.2 HTML and CSS
Basic HTML Elements
Tag Attributes
More About CSS
More HTML5 Elements
16.3 Interactive Web Pages
Java Applets
Java Server Pages
16.4 XML
16.5 Social Networks
Summary
Ethical Issues: Gambling and the Internet
Key Terms
Exercises
Thought Questions
Chapter 17 Computer Security
17.1 Security at All Levels
Information Security
17.2 Preventing Unauthorized Access
Passwords
CAPTCHA
Fingerprint Analysis
17.3 Malicious Code
Antivirus Software
Security Attacks
17.4 Cryptography
17.5 Protecting Your Information Online
Security and Portable Devices
WikiLeaks
17

Summary
Ethical Issues: Blogging
Key Terms
Exercises
Thought Questions
8 In Conclusion
Chapter 18 Limitations of Computing
18.1 Hardware
Limits on Arithmetic
Limits on Components
Limits on Communications
18.2 Software
Complexity of Software
Current Approaches to Software Quality
Notorious Software Errors
18.3 Problems
Comparing Algorithms
Turing Machines
Halting Problem
Classification of Algorithms
Summary
Ethical Issues: Therac-25: Anatomy of a Disaster
Key Terms
Exercises
Thought Questions

Glossary
Endnotes
Index
18

PREFACE
Choice of Topics
In putting together the outline of topics for this CS0 text, we used many sources. We
looked at course catalogue descriptions and book outlines, and we administered a
questionnaire designed to find out what you, our colleagues, thought should be included in
such a course. We asked you and ourselves to do the following:
■ Please list four topics that you feel students should master in a CS0 course if this is
the only computer science course they will take during their college experience.
■ Please list four topics that you would like students entering your CS1 course to have
mastered.
■ Please list four additional topics that you would like your CS1 students to be
familiar with.
The strong consensus that emerged from the intersections of these sources formed the
working outline for this book. Students who master this material before taking CS1 have a
strong foundation upon which to build their knowledge of computer science. Although our
intention was to write a CS0 text, our reviewers have pointed out that the material also
forms a strong breadth-first background that can also serve as a companion to a
programming-language introduction to computer science.
Rationale for Organization
This book begins with the history of hardware and software, showing how a computer
system is like an onion. The processor and its machine language form the heart of the
onion, and layers of software and more sophisticated hardware have been added around this
heart, layer by layer. At the next layer, higher-level languages such as FORTRAN, Lisp,
Pascal, C, C++, and Java were introduced parallel to the ever-increasing exploration of the
programming process, using such tools as top-down design and object-oriented design.
Over time, our understanding of the role of abstract data types and their implementations
matured. The operating system, with its resource-management techniques—including files
on ever-larger, faster secondary storage media—developed to surround and manage these
programs.
The next layer of the computer system “onion” is composed of sophisticated general-
purpose and special-purpose software systems that overlay the operating system.
Development of these powerful programs was stimulated by theoretical work in computer
science, which makes such programs possible. The final layer comprises networks and
19

network software—that is, the tools needed for computers to communicate with one
another. The Internet and the World Wide Web put the finishing touches to this layer, and
this text culminates with a discussion of security issues affecting our interaction online.
As these layers have grown over the years, the user has become increasingly insulated
from the computer system’s hardware. Each of these layers provides an abstraction of the
computing system beneath it. As each layer has evolved, users of the new layer have joined
with users of inner layers to create a very large workforce in the high-tech sector of the
global economy. This book is designed to provide an overview of the layers, introducing the
underlying hardware and software technologies, in order to give students an appreciation
and understanding of all aspects of computing systems.
Having used history to describe the formation of the onion from the inside out, we
were faced with a design choice: We could look at each layer in depth from the inside out
or the outside in. The outside-in approach was very tempting. We could peel the layers off
one at a time, moving from the most abstract layer to the concrete machine. However,
research has shown that students understand concrete examples more easily than abstract
ones, even when the students themselves are abstract thinkers. Thus, we have chosen to
begin with the concrete machine and examine the layers in the order in which they were
created, trusting that a thorough understanding of one layer makes the transition to the
next abstraction easier for the students.
Changes in the Sixth Edition
As always when planning a revision, we asked our colleagues, including many current users
of the text, to give us feedback. We appreciate the many thoughtful and insightful
20

responses we received.
Updates in the Sixth Edition include a considerable overhaul of Chapters 15 and 16,
which are about networks and the World Wide Web. We include new information about
wireless networks, as well as updates to the top-level domains (TLDs) that are now
available. In light of recent developments in U.S. oversight, we added a discussion about
who controls the Internet. Screenshots and discussions of ping and traceroute utilities are
now included, as well as an enhanced discussion about mobile computing. We completely
rewrote the section on HTML in Chapter 16 to reflect the most up-to-date practices and
the use of Cascading Style Sheets (CSS). We updated the section on social networks and
added a new discussion of web-based analytics.
In addition to these and other updates, the common features throughout the book have
been completely revised and augmented. The “Ethical Issues” sections at the end of each
chapter have been brought up to date. The “Did You Know?” sidebars have been updated
throughout the book as well, with the addition of several more that reflect new and novel
topics. Finally, the biographical sections throughout have been updated.
The Sixth Edition features a brand new design and layout, with all figures redrawn and
photos updated throughout.
Of course, we also made minor revisions throughout the book to improve and update
the coverage, presentation, and examples.
Synopsis
Chapter 1 lays the groundwork, as described in the “Rationale for This Book’s
Organization” section above. Chapters 2 and 3 step back and examine a layer that is
embodied in the physical hardware. We call this the “information layer” because it reflects
how data is represented in the computer. Chapter 2 covers the binary number system and
its relationship to other number systems such as decimal (the one we humans use on a daily
basis). Chapter 3 investigates how we take the myriad types of data we manage—numbers,
text, images, audio, and video—and represent them in a computer in binary format.
Chapters 4 and 5 discuss the hardware layer. Computer hardware includes devices such
as transistors, gates, and circuits, all of which control the flow of electricity in fundamental
ways. This core electronic circuitry gives rise to specialized hardware components such as
the computer’s central processing unit (CPU) and memory. Chapter 4 covers gates and
electronic circuits; Chapter 5 focuses on the hardware components of a computer and how
they interact within a von Neumann architecture.
Chapters 6 through 9 examine aspects of the programming layer. Chapter 6 explores
the concepts of both machine language and assembly language programming using Pep/8, a
simulated computer. We discuss the functionality of pseudocode as a way to write
algorithms. The concepts of looping and selection are introduced here, expressed in
pseudocode, and implemented in Pep/8.
Chapter 7 examines the problem-solving process as it relates to both humans and
computers. George Polya’s human problem-solving strategies guide the discussion. Top-
down design is presented as a way to design simple algorithms. We choose classic searching
and sorting algorithms as the context for the discussion of algorithms. Because algorithms
operate on data, we examine ways to structure data so that it can be more efficiently
21

processed. We also introduce subalgorithm (subprogram) statements.
Chapter 8 takes a step further toward abstraction, exploring abstract data types and
containers: composite structures for which we know only properties or behaviors. Lists,
sorted lists, stacks, queues, binary search trees, and graphs are discussed. The section on
subalgorithms is expanded to include reference and value parameters and parameter
passing.
Chapter 9 covers the concepts of high-level programming languages. Because many
prominent high-level languages include functionality associated with object-oriented
programming, we detour and first present this design process. Language paradigms and the
compilation process are discussed. Pseudocode concepts are illustrated in brief examples
from four programming languages: Python, Visual Basic .NET, C++, and Java.
Chapters 10 and 11 cover the operating system layer. Chapter 10 discusses the resource
management responsibilities of the operating system and presents some of the basic
algorithms used to implement these tasks. Chapter 11 focuses on file systems, including
what they are and how they are managed by the operating system.
Chapters 12 through 14 cover the application layer. This layer is made up of the
general-purpose and specialized application programs that are available to the public for
solving programs. We divide this layer into the sub-disciplines of computer science upon
which these programs are based. Chapter 12 examines information systems, Chapter 13
examines artificial intelligence, and Chapter 14 examines simulation, graphics, gaming, and
other applications.
Chapters 15 through 17 cover the communication layer. Chapter 15 presents the
theoretical and practical aspects of computers communicating with each other. Chapter 16
discusses the World Wide Web and the various technologies involved. Chapter 17
examines computer security and keeping information protected in the modern information
age.
Chapters 2 through 17 are about what a computer can do and how. Chapter 18
concludes the text with a discussion of the inherent limitations of computer hardware and
software, including the problems that can and cannot be solved using a computer. We
present Big-O notation as a way to talk about the efficiency of algorithms so that the
categories of algorithms can be discussed, and we use the Halting problem to show that
some problems are unsolvable.
The first and last chapters form bookends: Chapter 1 describes what a computing
system is and Chapter 18 cautions about what computing systems cannot do. The chapters
between take an in-depth look at the layers that make up a computing system.
Why Not a Language?
The original outline for this book included an “Introduction to Java” chapter. Some of our
reviewers were ambivalent about including a language at all; others wondered why Java
would be included and not C++. We decided to leave the choice to the user. Introductory
chapters, formatted in a manner consistent with the design of this book, are available for
Java, C++, JavaScript, Visual Basic. NET, Python, SQL, Ruby, Perl, Alice, and Pascal on
the book’s website and in hard copy through Jones & Bartlett Learning.
If the students have enough knowledge and experience to master the introductory
22

syntax and semantics of a language in addition to the background material in this book,
simply have the students download the appropriate chapter. As an alternative, one or all of
these chapters can be used to enrich the studies of those who have stronger backgrounds.
Special Features
We have included three special features in this text in order to emphasize the history and
breadth of computing as well as the moral obligations that come with new technology.
?
Virtual games and national security
U.S. and British spies have infiltrated the fantasy world of virtual games. A 2008 National Security Agency (NSA)
document declared that virtual games provide a “target-rich communication network” that allows intelligence
suspects a way to communicate and “hide in plain sight.”
4
Biographies
Each chapter includes a short biography of someone who has made a significant
contribution to computing as we know it. The people honored in these sections range from
those who contributed to the data layer, such as George Boole and Ada Lovelace, to those
who have contributed to the communication layer, such as Doug Engelbart and Tim
Berners-Lee. These biographies give students a taste of history and introduce them to the
23

men and women who are pioneers in the world of computing.
Did You Know
Our second feature (the “Did You Know?” sections indicated by a question mark)
comprises sidebars that include interesting tidbits of information from the past, present,
and future. They are garnered from history, current events, and the authors’ personal
experiences. These little vignettes are designed to amuse, inspire, intrigue, and, of course,
educate.
Ethical Issues
Our third feature is an “Ethical Issues” section that is included in each chapter. These
sections illustrate the fact that along with the advantages of computing come
responsibilities for and consequences of its use. Privacy, hacking, viruses, and free speech
are among the topics discussed. Following the exercises in each chapter, a “Thought
Questions” section asks stimulating questions about these ethical issues as well as chapter
content.
Color and Typography Are Signposts
The layers into which the book is divided are color coded within the text. The opening
spread for each chapter shows an image of the onion in which the outermost color
corresponds to the current layer. This color is repeated in header bars and section numbers
throughout the layer. Each opening spread also visually indicates where the chapter is
within the layer and the book.
We have said that the first and last chapters form bookends. Although they are not part
of the layers of the computing onion, these chapters are color coded like the others. Open
24

the book anywhere and you can immediately tell where you are within the layers of
computing.
To visually separate the abstract from the concrete in the programming layer, we use
different fonts for algorithms, including identifiers in running text, and program code. You
know at a glance whether the discussion is at the logical (algorithmic) level or at the
programming-language level. In order to distinguish visually between an address and the
contents of an address, we color addresses in orange.
Color is especially useful in Chapter 6, “Low-Level Programming Languages and
Pseudocode.” Instructions are color coded to differentiate the parts of an instruction. The
operation code is blue, the register designation is clear, and the addressing mode specifier is
green. Operands are shaded gray. As in other chapters, addresses are in orange.
Instructor Resources
For the instructor, slides in PowerPoint format, a test bank, and answers to the book’s end-
of-chapter exercises are available for free download at http://go.jblearning.com/CSI6e.
25

ACKNOWLEDGMENTS
Our adopters have been most helpful during this revision. To those who took the time to
respond to our online survey: Thanks to all of you. We are also grateful to the reviewers of
the previous editions of the text:
Tim Bower, Kansas State University
Mikhail Brikman, Salem State College
Jacques Carette, McMaster University
Howard Francis, Pikeville College
Jim Jones, Graceland University
Murray Levy, West Los Angeles College
Lew Lowther, York University
Jeffrey McConnell, Canisius College
Richard Schlesinger, Kennesaw State University
Richard Spinello, Boston College
Herman Tavani, Rivier College
Amy Woszczynski, Kennesaw State University
C. Michael Allen, UNC Charlotte
Lofton Bullard, Florida Atlantic University
Cerian Jones, University of Alberta
Calvin Ribbens, Virginia Tech
Susan Sells, Wichita State University
R. Mark Meyer, Canisius College
Tom Wiggen, University of North Dakota
Mary Dee Harris, Chris Edmonson-Yurkanan, Ben Kuipers, and Glenn Downing, The
University of Texas at Austin
Dave Stauffer, Penn State
John McCormick, University of Northern Iowa
Dan Joyce, Villanova University
Mike Goldwasser, St. Louis University
Andrew Harrington, Loyola University Chicago
Daniel R. Collins, Mass Bay Community College
J. Stanley Warford, Pepperdine University
Richard C. Detmer, Middle Tennessee State University
Chip Weems, University of Massachusetts Amherst
Heather Chandler, Westwood College
Mark Holthouse, Westwood High School
Robert Vermilyer, St. Thomas Aquinas College
Bob Blucher, Lane Community College
Dale Fletter, Folsom Lake College
26

Dr. Jerry Westfall, Liberty University
Dwayne Towell, Abilene Christian University
Kara Nance, University of Alaska
Lisa Michaud, Merrimack College
Jeffrey Bergamini, Mendocino College
Johanna Horowitz, Siena College
Lonnie R. Nelson, Hannibal-LaGrange University
Marie Hartlein, Montgomery County Community College
Mark Terwilliger, Lake Superior State University
Patricia Roth Pierce, Southern Polytechnic State University
Quentin J. White, Sr., Palomar College
Rakesh Arya, University of Maryland Eastern Shore
William Honig, Loyola University Chicago
Barbara Zimmerman, Villanova University
Maria Jump, PhD, King’s College
Joe Pistone, Palomar College
Derek Merck, Georgia Perimeter College.
Special thanks to Jeffrey McConnell of Canisius College, who wrote the graphics
section in Chapter 14; Herman Tavani of Rivier College, who helped us revise the “Ethical
Issues” sections; Richard Spinello of Boston College for his essay on the ethics of blogging;
and Paul Toprac, Associate Director of Game Development at The University of Texas at
Austin, for his contributions on gaming.
We appreciate and thank our reviewers and colleagues who provided advice and
recommendations for the content in this Sixth Edition:
David Adams, Grove City College
Marie Arvi, Salisbury University
Bill Cole, Sierra College-Rocklin
Richard Croft, Eastern Oregon University
Linda Ehley, Alverno College
Janet Helwig, Dominican University
James Hicks, Los Angeles Southwest College
Aparna Mahadev, Worcester State University
Mia Moore, Clark Atlanta University
S. Monisha Pulimood, The College of New Jersey
Warren W. Sheaffer, Saint Paul College
Robert Yacobellis, Loyola University Chicago
We also thank the many people at Jones & Bartlett Learning who contributed so much,
especially Laura Pagluica, Acquisitions Editor; Taylor Ferracane, Editorial Assistant; and
Amy Rose, Director of Production.
I must also thank my tennis buddies for keeping me fit, my bridge buddies for keeping my
mind alert, and my family for keeping me grounded.
—ND
27

I’d like to thank my family for their support.
—JL
28

SPECIAL FEATURES
Interspersed throughout Computer Science Illuminated, Sixth Edition are two special features
of note: Ethical Issues and Biographies. A list of each is provided below for immediate
access.
ETHICAL ISSUES
Digital Divide
The FISA Court
The Fallout from Snowden’s Revelations
Codes of Ethics
Is Privacy a Thing of the Past?
Software Piracy
Open-Source Software
Workplace Monitoring
Hoaxes and Scams
Medical Privacy: HIPAA
Privacy: Opt-In or Opt-Out?
Politics and the Internet: The Candidate’s View
Initial Public Offerings
Gaming as an Addiction
The Effects of Social Networking
Gambling and the Internet
Blogging
Therac-25: Anatomy of a Disaster
BIOGRAPHIES
Ada Lovelace, the First Programmer
Grace Murray Hopper
29

Bob Bemer
George Boole
John Vincent Atanasoff
Konrad Zuse
George Polya
John von Neumann
Edsger Dijkstra
Steve Jobs
Tony Hoare
Daniel Bricklin
Herbert A. Simon
Ivan Sutherland
Doug Engelbart
Tim Berners-Lee
Mavis Batey
Alan Turing
30

LAYING THE GROUNDWORK
Laying the Groundwork
1 The Big Picture
The Information Layer
2 Binary Values and Number Systems
3 Data Representation
The Hardware Layer
4 Gates and Circuits
5 Computing Components
The Programming Layer
6 Low-Level Programming Languages and Pseudocode
7 Problem Solving and Algorithms
8 Abstract Data Types and Subprograms
9 Object-Oriented Design and High-Level Programming Languages
The Operating Systems Layer
10 Operating Systems
11 File Systems and Directories
The Applications Layer
12 Information Systems
13 Artificial Intelligence
14 Simulation, Graphics, Gaming, and Other Applications
The Communications Layer
15 Networks
16 The World Wide Web
17 Computer Security
In Conclusion
18 Limitations of Computing
31

1 THE BIG PICTURE
This book is a tour through the world of computing. We explore how computers work—
what they do and how they do it, from bottom to top, inside and out. Like an orchestra, a
computer system is a collection of many different elements, which combine to form a
whole that is far more than the sum of its parts. This chapter provides the big picture,
giving an overview of the pieces that we slowly dissect throughout the book and putting
those pieces into historical perspective.
Hardware, software, programming, web surfing, and email are probably familiar terms to
you. Some of you can define these and many more computer-related terms explicitly,
whereas others may have only a vague, intuitive understanding of them. This chapter gets
everyone on relatively equal footing by establishing common terminology and creating the
platform from which we will dive into our exploration of computing.
GOALS
After studying this chapter, you should be able to:

■ describe the layers of a computer system.
■ describe the concept of abstraction and its relationship to computing.
■ describe the history of computer hardware and software.
■ describe the changing role of the computer user.
■ distinguish between systems programmers and applications programmers.
■ distinguish between computing as a tool and computing as a discipline.
1.1 Computing Systems
In this book we explore various aspects of computing systems. Note that we use the term
computing system, not just computer. A computer is a device. A computing system, by
contrast, is a dynamic entity, used to solve problems and interact with its environment. A
computing system is composed of hardware, software, and the data that they manage.
Computer hardware is the collection of physical elements that make up the machine and
its related pieces: boxes, circuit boards, chips, wires, disk drives, keyboards, monitors,
printers, and so on. Computer software is the collection of programs that provide the
instructions that a computer carries out. And at the very heart of a computer system is the
information that it manages. Without data, the hardware and software are essentially
useless.
32

Computing system Computer hardware, software, and data, which interact to solve problems
Computer hardware The physical elements of a computing system
Computer software The programs that provide the instructions that a computer executes
The general goals of this book are threefold:
■ To give you a solid, broad understanding of how a computing system works
■ To develop an appreciation for and understanding of the evolution of modern
computing systems
■ To give you enough information about computing so that you can decide whether
you wish to pursue the subject further
The rest of this section explains how computer systems can be divided into abstract
layers and how each layer plays a role. The next section puts the development of computing
hardware and software into historical context. This chapter concludes with a discussion
about computing as both a tool and a discipline of study.
Layers of a Computing System
A computing system is like an onion, made up of many layers. Each layer plays a specific
role in the overall design of the system. These layers are depicted in FIGURE 1.1 and form
the general organization of this book. This is the “big picture” that we will continually
return to as we explore different aspects of computing systems.
You rarely, if ever, take a bite out of an onion as you would an apple. Rather, you
separate the onion into concentric rings. Likewise, in this book we explore aspects of
computing one layer at a time. We peel each layer separately and explore it by itself. Each
layer, in itself, is not that complicated. In fact, a computer actually does only very simple
tasks—it just does them so blindingly fast that many simple tasks can be combined to
accomplish larger, more complicated tasks. When the various computer layers are all
brought together, each playing its own role, amazing things result from the combination of
these basic ideas.
Let’s discuss each of these layers briefly and identify where in this book these ideas are
explored in more detail. We essentially work our way from the inside out, which is
sometimes referred to as a bottom-up approach.
33

FIGURE 1.1 The layers of a computing system
The innermost layer, information, reflects the way we represent information on a
computer. In many ways this is a purely conceptual level. Information on a computer is
managed using binary digits, 1 and 0. So to understand computer processing, we must first
understand the binary number system and its relationship to other number systems (such as
the decimal system, the one humans use on a daily basis). Then we can turn our attention
to how we take the myriad types of information we manage—numbers, text, images, audio,
and video—and represent them in a binary format. Chapters 2 and 3 explore these issues.
The next layer, hardware, consists of the physical hardware of a computer system.
Computer hardware includes devices such as gates and circuits, which control the flow of
electricity in fundamental ways. This core electronic circuitry gives rise to specialized
hardware components such as the computer’s central processing unit (CPU) and memory.
Chapters 4 and 5 of the book discuss these topics in detail.
The programming layer deals with software, the instructions used to accomplish
computations and manage data. Programs can take many forms, be performed at many
levels, and be implemented in many languages. Yet, despite the enormous variety of
programming issues, the goal remains the same: to solve problems. Chapters 6 through 9
explore many issues related to programming and the management of data.
Every computer has an operating system (OS) to help manage the computer’s resources.
Operating systems, such as Windows XP, Linux, or Mac OS, help us interact with the
computer system and manage the way hardware devices, programs, and data interact.
Knowing what an operating system does is key to understanding the computer in general.
These issues are discussed in Chapters 10 and 11.
The previous (inner) layers focus on making a computer system work. The applications
layer, by contrast, focuses on using the computer to solve specific real-world problems. We
run application programs to take advantage of the computer’s abilities in other areas, such
as helping us design a building or play a game. The spectrum of area-specific computer
software tools is far-reaching and involves specific subdisciplines of computing, such as
information systems, artificial intelligence, and simulation. Application systems are
discussed in Chapters 12, 13, and 14.
Computers no longer exist in isolation on someone’s desktop. We use computer
technology to communicate, and that communication is a fundamental layer at which
34

computing systems operate. Computers are connected into networks so that they can share
information and resources. The Internet, for example, evolved into a global network, so
there is now almost no place on Earth that you cannot communicate with via computing
technology. The World Wide Web makes that communication relatively easy; it has
revolutionized computer use and made it accessible to the general public. Chapters 15 and
16 discuss these important issues of computing communication.
The use of computing technology can result in increased security hazards. Some issues
of security are dealt with at low levels throughout a computer system. Many of them,
though, involve keeping our personal information secure. Chapter 17 discusses several of
these issues.
Most of this book focuses on what a computer can do and how it does it. We conclude
with a discussion of what a computer cannot do, or at least cannot do well. Computers have
inherent limitations on their ability to represent information, and they are only as good as
their programming makes them. Furthermore, it turns out that some problems cannot be
solved at all. Chapter 18 examines these limitations of computers.
Sometimes it is easy to get so caught up in the details that we lose perspective on the
big picture. Try to keep that in mind as you progress through the information in this book.
Each chapter’s opening page reminds you of where we are in the various layers of a
computing system. The details all contribute a specific part to a larger whole. Take each
step in turn and you will be amazed at how well it all falls into place.
Abstraction
The levels of a computing system that we just examined are examples of abstraction. An
abstraction is a mental model, a way to think about something, that removes or hides
complex details. An abstraction leaves only the information necessary to accomplish our
goal. When we are dealing with a computer on one layer, we don’t need to be thinking
about the details of the other layers. For example, when we are writing a program, we don’t
have to concern ourselves with how the hardware carries out the instructions. Likewise,
when we are running an application program, we don’t have to be concerned with how that
program was written.
Abstraction A mental model that removes complex details
Numerous experiments have shown that a human being can actively manage about
seven (plus or minus two, depending on the person) pieces of information in short-term
memory at one time. This is called Miller’s Law, based on the psychologist who first
investigated it.
1
Other pieces of information are available to us when we need them, but
when we focus on a new piece, something else falls back into secondary status.
This concept is similar to the number of balls a juggler can keep in the air at one time.
Human beings can mentally juggle about seven balls at once, and when we pick up a new
one, we have to drop another. Seven may seem like a small number, but the key is that each
ball can represent an abstraction, or a chunk of information. That is, each ball we are
juggling can represent a complex topic as long as we can think about it as one idea.
We rely on abstractions every day of our lives. For example, we don’t need to know
35

how a car works to drive one to the store. That is, we don’t really need to know how the
engine works in detail. We need to know only some basics about how to interact with the
car: how the pedals and knobs and steering wheel work. And we don’t even have to be
thinking about all of those things at the same time. See FIGURE 1.2.
FIGURE 1.2 A car engine and the abstraction that allows us to use it
© aospan/Shutterstock, Inc.; © Syda Productions/Shutterstock, Inc.
Even if we do know how an engine works, we don’t have to think about it while
driving. Imagine if, while driving, we had to constantly think about how the spark plugs
ignite the fuel that drives the pistons that turn the crankshaft. We’d never get anywhere! A
car is much too complicated for us to deal with all at once. All the technical details would
be too many balls to juggle at the same time. But once we’ve abstracted the car down to the
way we interact with it, we can deal with it as one entity. The irrelevant details are ignored,
at least for the moment.
Information hiding is a concept related to abstraction. A computer programmer often
tries to eliminate the need or ability of one part of a program to access information located
in another part. This technique keeps the pieces of the program isolated from each other,
which reduces errors and makes each piece easier to understand. Abstraction focuses on the
external view—the way something behaves and the way we interact with it. Information
hiding is a design feature that gives rise to the abstractions that make something easier to
work with. Information hiding and abstraction are two sides of the same coin.
Information hiding A technique for isolating program pieces by eliminating the ability for one piece to access the
information in another
Abstract art, as the name implies, is another example of abstraction. An abstract
painting represents something but doesn’t get bogged down in the details of reality.
Consider the painting shown in FIGURE 1.3, entitled Nude Descending a Staircase. You
can see only the basic hint of the woman and the staircase, because the artist is not
interested in the details of exactly how the woman or the staircase looks. Those details are
irrelevant to the effect the artist is trying to create. In fact, the realistic details would get in
the way of the issues that the artist thinks are important.
Abstraction is the key to computing. The layers of a computing system embody the idea
of abstraction. And abstractions keep appearing within individual layers in various ways as
36

well. In fact, abstraction can be seen throughout the entire evolution of computing systems,
which we explore in the next section.
FIGURE 1.3 Marcel Duchamp discussing his abstract painting Nude Descending a Staircase
© CBS/Landov
1.2 The History of Computing
The historical foundation of computing goes a long way toward explaining why computing
systems today are designed as they are. Think of this section as a story whose characters and
events have led to the place we are now and form the foundation of the exciting future to
come. We examine the history of computing hardware and software separately because each
has its own impact on how computing systems evolved into the layered model we use as the
outline for this book.
This history is written as a narrative, with no intent to formally define the concepts
discussed. In subsequent chapters, we return to these concepts and explore them in more
detail.
A Brief History of Computing Hardware
The devices that assist humans in various forms of computation have their roots in the
ancient past and have continued to evolve until the present day. Let’s take a brief tour
through the history of computing hardware.
37

Early History
Many people believe that Stonehenge, the famous collection of rock monoliths in Great
Britain, is an early form of a calendar or astrological calculator. The abacus, which appeared
in the sixteenth century BC, was developed as an instrument to record numeric values and
on which a human can perform basic arithmetic.
In the middle of the seventeenth century, Blaise Pascal, a French mathematician, built
and sold gear-driven mechanical machines, which performed whole-number addition and
subtraction. Later in the seventeenth century, a German mathematician, Gottfried Wilhelm
von Leibniz, built the first mechanical device designed to do all four whole-number
operations: addition, subtraction, multiplication, and division. Unfortunately, the state of
mechanical gears and levers at that time was such that the Leibniz machine was not very
reliable.
In the late eighteenth century, Joseph Jacquard developed what became known as
Jacquard’s loom, used for weaving cloth. The loom used a series of cards with holes punched
in them to specify the use of specific colored thread and therefore dictate the design that
was woven into the cloth. Although not a computing device, Jacquard’s loom was the first
to make use of an important form of input: the punched card.
?
Beyond all dreams
“Who can foresee the consequences of such an invention? The Analytical Engine weaves algebraic patterns just as
the Jacquard loom weaves flowers and leaves. The engine might compose elaborate and scientific pieces of music of
any degree of complexity or extent.”
—Ada, Countess of Lovelace, 1843
2
Stonehenge Is Still a Mystical Place
© vencavolrab/iStock/Thinkstock
Stonehenge, a Neolithic stone structure that rises majestically out of the Salisbury Plain
in England, has fascinated humans for centuries. It is believed that Stonehenge was
erected over several centuries beginning in about 2180 BC. Its purpose is still a mystery,
although theories abound. At the summer solstice, the rising sun appears behind one of
the main stones, giving the illusion that the sun is balancing on the stone. This has led
38

to the early theory that Stonehenge was a temple. Another theory, first suggested in the
middle of the twentieth century, is that Stonehenge could have been used as an
astronomical calendar, marking lunar and solar alignments. Yet a third theory is that
Stonehenge was used to predict eclipses. The latest research now shows that Stonehenge
was intended for and used as a cemetery.
3
Human remains, from about 3000 BC until
2500 BC when the first large stones were raised, have been found. Regardless of why it
was built, there is a mystical quality about the place that defies explanation.
It wasn’t until the nineteenth century that the next major step was taken, this time by a
British mathematician. Charles Babbage designed what he called his analytical engine. His
design was too complex for him to build with the technology of his day, so it was never
implemented. His vision, however, included many of the important components of today’s
computers. Babbage’s design was the first to include a memory so that intermediate values
did not have to be reentered. His design also included the input of both numbers and
mechanical steps, making use of punched cards similar to those used in Jacquard’s loom.
Ada Augusta, Countess of Lovelace, was a very romantic figure in the history of
computing. Ada, the daughter of Lord Byron (the English poet), was a skilled
mathematician. She became interested in Babbage’s work on the analytical engine and
extended his ideas (as well as correcting some of his errors). Ada is credited with being the
first programmer. The concept of the loop—a series of instructions that repeat—is
attributed to her. The programming language Ada, used largely by the U.S. Department of
Defense, is named for her.
During the later part of the nineteenth century and the beginning of the twentieth
century, computing advances were made rapidly. William Burroughs produced and sold a
mechanical adding machine. Dr. Herman Hollerith developed the first electro-mechanical
tabulator, which read information from a punched card. His device revolutionized the
census taken every ten years in the United States. Hollerith later formed a company known
today as IBM.
In 1936, a theoretical development took place that had nothing to do with hardware
per se but profoundly influenced the field of computer science. Alan M. Turing, another
British mathematician, invented an abstract mathematical model called a Turing machine,
laying the foundation for a major area of computing theory. The most prestigious award
given in computer science (equivalent to the Fielding Medal in mathematics or a Nobel
Prize in other sciences) is the Turing Award, named for Alan Turing. A recent Broadway
play deals with his life. Analysis of the capabilities of Turing machines is a part of the
theoretical studies of all computer science students.
In the mid to late 1930s, work on building a computing machine continued around the
world. In 1937, George Stibitz constructed a 1-bit binary adder using relays. (See Chapter
4.) Later that year, Claude E. Shannon published a paper about implementing symbolic
logic using relays. In 1938, Konrad Zuse of Berlin built the first mechanical binary
programmable computer. (See biography of Konrad Zuse in Chapter 6.)
By the outbreak of World War II, several general-purpose computers were under design
and construction. In London in 1943, Thomas Flowers built the Colossus, considered by
many to be the first all-programmable electronic digital computer (FIGURE 1.4). In 1944,
the IBM Automatic Sequence Controlled Calculator was given to Harvard; it was
39

subsequently known as the Harvard Mark I. The ENIAC, pictured in FIGURE 1.5, was
unveiled in 1946. John von Neumann, who had served as a consultant on the ENIAC
project, started work on another machine known as EDVAC, which was completed in
1950. In 1951, the first commercial computer, UNIVAC I, was delivered to the U.S.
Bureau of the Census. The UNIVAC I was the first computer used to predict the outcome
of a presidential election.
4
The early history that began with the abacus ended with the delivery of the UNIVAC I.
With the building of that machine, the dream of a device that could rapidly manipulate
numbers was realized; the search was ended. Or was it? Some experts predicted at that time
that a small number of computers would be able to handle the computational needs of
mankind. What they didn’t realize was that the ability to perform fast calculations on large
amounts of data would radically change the very nature of fields such as mathematics,
physics, engineering, and economics. That is, computers made those experts’ assessments of
what needed to be calculated entirely invalid.
5
FIGURE 1.4 The Colossus, the first all-programmable digital computer
© Pictorial Press Ltd/Alamy Images
40

FIGURE 1.5 The ENIAC, a World War II–era computer
Courtesy of U.S. Army.
After 1951, the story becomes one of the ever-expanding use of computers to solve
problems in all areas. From that point, the search has focused not only on building faster,
bigger devices, but also on developing tools that allow us to use these devices more
productively. The history of computing hardware from this point on is categorized into
several “generations” based on the technology they employed.
Counting Precedes Writing
It took about 4000 years to fully reduce three-dimensional tokens to written signs. It all
began about 7500 BC, when farmers made counters of clay in a dozen shapes to help
keep track of their goods. For example, a cone stood for a small measure of grain, a
sphere for a large measure of grain, and a cylinder for an animal. Four small measures of
grain were represented by four cones. Approximately 8000 of these tokens have been
found from Palestine, Anatolia, Syria, Mesopotamia, and Iran.
Approximately 3500 BC, after the rise of the city-states, administrators started using
clay balls as envelopes to hold the tokens. Some of these envelopes bore impressions of
the tokens they contained. The next step occurred between 3300 and 3200 BC, when
record keepers started just using the impression of the tokens on clay balls, dispensing
with the tokens themselves. Thus it took approximately 4000 years to reduce three-
dimensional tokens to written signs.
Around 3100 BC, styluses were used to draw the tokens rather than impressing the
tokens on the tables. This change led to the breaking of the one-to-one correspondence
between symbol and object. Ten jars of oil were represented by a jar of oil and a symbol
for ten. New signs were not created to express abstract numbers, but old signs took on
new meaning. For example, the cone sign, formerly representing a small measure of
grain, became the symbol for “1,” and the sphere (a large measure of grain) came to
mean “10.” Now 33 jars of oil could be represented by 10 + 10 + 10 + 1 + 1 + 1 and the
41

symbol for “oil.”
Once abstract numerals were created, the signs for goods and the signs for numbers
could evolve in different ways. Thus writing was derived from counting.
6
First Generation (1951–1959)
Commercial computers in the first generation (from approximately 1951 to 1959) were
built using vacuum tubes to store information. A vacuum tube, shown in FIGURE 1.6,
generated a great deal of heat and was not very reliable. The machines that used them
required heavy-duty air conditioning and frequent maintenance. They also required very
large, specially built rooms.
FIGURE 1.6 A vacuum tube
© SPbPhoto/Shutterstock, Inc.
The primary memory device of this first generation of computers was a magnetic drum
that rotated under a read/write head. When the memory cell that was being accessed
rotated under the read/write head, the data was written to or read from that place.
The input device was a card reader that read the holes punched in an IBM card (a
descendant of the Hollerith card). The output device was either a punched card or a line
printer. By the end of this generation, magnetic tape drives had been developed that were
much faster than card readers. Magnetic tapes are sequential storage devices, meaning that
the data on the tape must be accessed one after another in a linear fashion.
Storage devices external to the computer memory are called auxiliary storage devices.
The magnetic tape was the first of these devices. Collectively, input devices, output devices,
and auxiliary storage devices became known as peripheral devices.
Second Generation (1959–1965)
The advent of the transistor (for which John Bardeen, Walter H. Brattain, and William B.
Shockley won a Nobel Prize) ushered in the second generation of commercial computers.
The transistor replaced the vacuum tube as the main component in the hardware. The
42

transistor, as shown in FIGURE 1.7, was smaller, more reliable, faster, more durable, and
cheaper.
The second generation also witnessed the advent of immediate-access memory. When
accessing information from a drum, the CPU had to wait for the proper place to rotate
under the read/write head. The second generation used memory made from magnetic cores,
tiny doughnut-shaped devices, each capable of storing one bit of information. These cores
were strung together with wires to form cells, and cells were combined into a memory unit.
Because the device was motionless and was accessed electronically, information was
available instantly.
FIGURE 1.7 A transistor, which replaced the vacuum tube
Courtesy of Dr. Andrew Wylie
Ada Lovelace, the First Programmer
7
On December 10, 1815 (the same year that George Boole was born), a daughter—
Augusta Ada Byron—was born to Anna Isabella (Annabella) Byron and George
Gordon, Lord Byron. At that time in England, Byron’s fame derived not only from his
poetry but also from his wild and scandalous behavior. The marriage was strained from
the beginning, and Annabella left Byron shortly after Ada’s birth. By April of 1816, the
two had signed separation papers. Byron left England, never to return. Throughout the
rest of his life he regretted that he was unable to see his daughter. At one point he wrote
of her,
I see thee not. I hear thee not.
But none can be so wrapt in thee.
Before he died in Greece, at age 36, he exclaimed,
43

Oh my poor dear child! My dear Ada!
My God, could I but have seen her!
Meanwhile, Annabella, who eventually was to become a baroness in her own right,
and who was educated as both a mathematician and a poet, carried on with Ada’s
upbringing and education. Annabella gave Ada her first instruction in mathematics, but
it soon became clear that Ada was gifted in the subject and should receive more
extensive tutoring. Ada received further training from Augustus DeMorgan, today
famous for one of the basic theorems of Boolean algebra. By age eight, Ada had
demonstrated an interest in mechanical devices and was building detailed model boats.
When she was 18, Ada visited the Mechanics Institute to hear Dr. Dionysius
Lardner’s lectures on the Difference Engine, a mechanical calculating machine being
built by Charles Babbage. She became so interested in the device that she arranged to be
introduced to Babbage. It was said that, upon seeing Babbage’s machine, Ada was the
only person in the room to understand immediately how it worked and to recognize its
significance. Ada and Charles Babbage became lifelong friends. She worked with him,
helping to document his designs, translating writings about his work, and developing
programs for his machines. In fact, Ada today is recognized as the first computer
programmer in history.
When Babbage designed his Analytical Engine, Ada foresaw that it could go beyond
arithmetic computations and become a general manipulator of symbols, thus having far-
reaching capabilities. She even suggested that such a device eventually could be
programmed with rules of harmony and composition so that it could produce
“scientific” music. In effect, Ada foresaw the field of artificial intelligence more than 150
years ago.
In 1842, Babbage gave a series of lectures in Turin, Italy, on his Analytical Engine.
One of the attendees was Luigi Menabrea, who was so impressed that he wrote an
account of Babbage’s lectures. At age 27, Ada decided to translate the account into
English, with the intent to add a few of her own notes about the machine. In the end,
her notes were twice as long as the original material, and the document, “The Sketch of
the Analytical Engine,” became the definitive work on the subject.
It is obvious from Ada’s letters that her “notes” were entirely her own and that
Babbage was acting as a sometimes unappreciated editor. At one point, Ada wrote to
him,
I am much annoyed at your having altered my Note. You know I am always willing
to make any required alterations myself, but that I cannot endure another person to
meddle with my sentences.
Ada gained the title “Countess of Lovelace” when she married Lord William
Lovelace. The couple had three children, whose upbringing was left to Ada’s mother
while Ada pursued her work in mathematics. Her husband was supportive of her work,
but for a woman of that day such behavior was considered almost as scandalous as some
of her father’s exploits.
Ada died in 1852, just one year before a working Difference Engine was built in
Sweden from one of Babbage’s designs. Like her father, Ada lived only to age 36, and
44

even though they led very different lives, she undoubtedly admired him and took
inspiration from his unconventional and rebellious nature. In the end, Ada asked to be
buried beside him at the family’s estate.
The magnetic disk, a new auxiliary storage device, was also developed during the second
computer hardware generation. The magnetic disk is faster than magnetic tape because each
data item can be accessed directly by referring to its location on the disk. Unlike a tape,
which cannot access a piece of data without accessing everything on the tape that comes
before it, a disk is organized so that each piece of data has its own location identifier, called
an address. The read/write heads of a magnetic disk can be sent directly to the specific
location on the disk where the desired information is stored.
Third Generation (1965–1971)
In the second generation, transistors and other components for the computer were
assembled by hand on printed circuit boards. The third generation was characterized by
integrated circuits (ICs), solid pieces of silicon that contained the transistors, other
components, and their connections. Integrated circuits were much smaller, cheaper, faster,
and more reliable than printed circuit boards. Gordon Moore, one of the co-founders of
Intel, noted that from the time of the invention of the IC, the number of circuits that could
be placed on a single integrated circuit was doubling each year. This observation became
known as Moore’s law.
8
Transistors also were used for memory construction, where each transistor represented
one bit of information. Integrated-circuit technology allowed memory boards to be built
using transistors. Auxiliary storage devices were still needed because transistor memory was
volatile; that is, the information went away when the power was turned off.
The terminal, an input/output device with a keyboard and screen, was introduced
during this generation. The keyboard gave the user direct access to the computer, and the
screen provided an immediate response.
?
Scientists build first nanotube computer
Scientists are examining the possibility of using carbon nanotubes, seamless cylinders of ultrapure carbon, as a basis
for future computers. As electrical conduction speeds of conventional silicon transistors begin to reach the limits of
the technology, the search is on for replacements that are faster than silicon. In 2013, scientists at Stanford
University built a working, although primitive, prototype of a computer using nanotube transistors made with these
unusual carbon fibers.
9
Fourth Generation (1971–?)
Large-scale integration characterizes the fourth generation. From several thousand transistors
on a silicon chip in the early 1970s, we had moved to a whole microcomputer on a chip by
the middle of this decade. Main memory devices are still made almost exclusively out of
45

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Barley Loaves

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Title: A Basket of Barley Loaves
Author: Mary Christina Miller
Release date: October 31, 2015 [eBook #50349]
Most recently updated: October 22, 2024
Language: English
Credits: Produced by Richard Hulse, Chris Pinfield and the Online
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*** START OF THE PROJECT GUTENBERG EBOOK A BASKET OF
BARLEY LOAVES ***

Transcriber's note.
The author is not listed on the title page but has
been identified as Mary Christina Miller.
A few apparent typographical errors have been
corrected.
Chapters II to XVIII begin with a short quotation
from Psalm 104. For technical reasons the
quotation marks have been omitted.
A BASKET
OF
BARLEY LOAVES.
BY THE
Author of "The High Mountain Apart" and "Sacramental Sabbaths."
"There is a lad here, which hath five barley loaves."—John vi. 9.
PHILADELPHIA:
PRESBYTERIAN BOARD OF PUBLICATION,

No. 1334 CHESTNUT STREET.
Entered according to Act of Congress, in the year 1870, by
THE TRUSTEES OF THE
PRESBYTERIAN BOARD OF PUBLICATION,
In the office of the Librarian of Congress, at Washington.
Westcott & Thomson ,
Stereotypers, Philada.
TO
MY FORMER PASTOR,
Rev. ALEXANDER DICKSON,
WHO TAUGHT ME
"THE WAY OF GOD MORE PERFECTLY,"

AND WHOSE THOUGHT S AND VERY WORDS ENTER LARGELY INTO
THESE PAGES,
I DEDICATE THIS
Basket of Barley Loaves.

EDITOR'S PREFACE.
To those who crave more of Christ in the soul and in the daily life,
to those who long for holiness and assurance, this Basket of Barley
Loaves will bring welcome refreshment and nourishment. The devout,
even though trembling, believer, who hungers after righteousness,
will here find that which will kindle his affections and lead them to
the only satisfying source of love and peace, Jesus Christ. What of
sweetness and strength there is in these meditations is due to God's
word, of which they are full. Sweeter than honey and the honey-
comb, more precious than silver or gold, was that word to the
Psalmist; and thence these chapters draw their flavor and force. By
them the weary, the needy, the longing, will be led nearer to Christ
and be more filled with the power of his love. May these few Barley
Loaves feed many thousands of hungry souls!
J. W. D.

CONTENTS.
PAGE
IJesus Sought and Found 11
IIHis Name 24
IIIThe Assurance 31
IVThe Perfect Work 41
VThe Chastening 52
VIThe Compassion 61
VIIThe Sympathy 69
VIIIThe Love 78
IXThe Life Abundant 85
XThe Forgiveness 90
XIThe Help 97
XIIThe Deliverance 102
XIIIThe Hearer of Prayer 107
XIVThe Reward 112
XVThe Soul's Portion 119
XVIThe Cross 127
XVIIThe Presence 131
XVIIIThe Appearing 136
XIXThe Conclusion 143

A BASKET
OF
BARLEY LOAVES.

T
I.
Jesus Sought and Found.
HE crowd was thronging and jostling. Eager and wistful faces
were turned to One who stood in the midst. His countenance
was mild and compassionate; and as I gazed upon him, a deep
desire filled my heart to know and follow this Man of Sorrows. With
swiftest steps I hurried on and pressed into the crowd. The lowly,
suffering woman was satisfied to touch the hem of his garments,
and it was enough. But I was not content until I had grasped his
hand. Yes, I put my hand in his—my guilty hand that nailed him to
the cross.
"Who touched me?" He turned, and we stood face to face. In
answer to his inquiry I whispered, "Lord, I will follow thee
whithersoever thou goest." A look of love glanced from his eye;
nearer he drew me to his side and whispered, "Beloved." Oh how it
thrilled my heart! Excess of joy choked my utterance, and I could
only grasp his hand more firmly and exclaim, "My Lord and my God!"
Tell me not now of loneliness and desolation. Jesus is mine, and
so we journey hand in hand; and as he whispers to me of love
unchangeable, I hide this sweet secret in my heart and answer, "I
am thine."
"They tell me," we said to an aged man, "that you have no rock
on which to plant your feet." "No rock?" he said, calmly, with a smile
—"no rock? Well, my creed does differ from yours. Mine is love to
God and love to my fellow-men. I do not believe such a man as
Jesus Christ ever lived. The world has had many saviours. Mine is a
principle—a rightening principle. I have tried all beliefs, and here I
am content to rest."
But we have not so learned Christ.

Infidels may tell me such a man never lived; humanitarians may
tell me he was mere man and no God; careless worldlings may tell
me there is no beauty in him that I should desire him; but from the
far-off region of light, beyond the mist-clouds that encircle the earth,
I hear a voice, calm in its majesty and tender in its tones: "I am
Alpha and Omega, the beginning and the ending, saith the Lord,
which is, and which was, and which is to come, the Almighty." "I am
the light of the world: he that followeth me shall not walk in
darkness, but shall have the light of life." "I am the Lord thy God,
the Holy One of Israel, thy Saviour." "I, even I, am the Lord; and
beside me there is no Saviour." "O Israel, thou hast destroyed
thyself, but in me is thine help." "I will ransom them from the power
of the grave; I will redeem them from death." "Come unto me, all ye
that labor and are heavy laden, and I will give you rest."
Hearing this voice I draw nearer. "Have I been so long time with
you, and yet hast thou not known me? Thou hast both seen him,
and he it is that talketh with thee." "Lord, I believe." "I know thee
who thou art, the Holy One of God." With the eye of faith I have
seen thee, and I can testify that "thou art fairer than the children of
men." With the hand of faith I have grasped thine, O thou "Friend
that stickest closer than a brother." And thou hast talked with me.
"Never man spake like this man." I cannot utter half the words Jesus
has spoken to my soul; but this I say: Into his hands I commit my
soul with all its interests; "for I know whom I have believed, and am
persuaded that he is able to keep that which I have committed unto
him against that day."
"O Jesus, Friend unfailing,
How dear thou art to me!
And, cares or fears assailing,
I find my strength in thee.
"I love to own, Lord Jesus,
Thy claims o'er me and mine;
Bought with thy blood most precious,
Whose can I be but thine?"

"As the late lamented Dudley Tyng was passing from the earthly
vineyard to his higher position in the heavenly," writes Boardman in
his book entitled "Him that Overcometh," "he said to his father, while
light fell upon him from the open gateway, 'Father, stand up for
Jesus.' Then, after advancing a little farther on into the fuller
effulgence, he spoke again, saying, 'Father, stand up in Jesus.' These
injunctions were reported by his father as they fell from the lips of
his son, and went abroad all over the land. The first one struck a
chord which vibrates still, and passed into a watchword for all
Christian enterprise and for all enterprising Christians, but the
second seemed to find no chord keyed up and ready to respond. It
is to be feared that this is indicative of the true state of the Christian
world to-day—for Christ, more than in him; and yet, if we may
believe the words of Christ himself, and the history of all the
progress of his kingdom, we have the secret of all power in these
two words, "in Jesus," with the converse of them, "Jesus in us."
"Abide in me, and I in you." Christ within is better even than
Christ beside us, as the apostles found after Pentecost. This is the
secret of all joy and the source of all strength.
To those who are just starting on the Christian pilgrimage we
would repeat these words of the Master, "Abide in me." Guide-books
are good, but a trusty guide is better. We might fill our pages with
minute directions concerning the way, but we would rather point to
Christ, who is the way. We remember that there are times when
travelers forget their guide-books and cling to their strong and sure-
footed guides.
Consider our Guide. He knows every step of the way, and he will
guide us with his eye. Let us meditate upon Christ till our hearts are
led to desire more intimate fellowship with him. "My meditation of
him shall be sweet"—"sweet" when I remember his name, his
character, his work, his promises and the peace he gives.
But it may be that some to whom these pages are addressed find
many dark threads of doubt woven into their meditation of Christ.
You have never, perhaps, been fully assured of your acceptance with

him; or, if confident at the commencement of your Christian course,
doubts and fears may have gathered around your pathway before
journeying very far into the wilderness. The chilling winds of unbelief
make winter in your soul. The days are short and cold; the nights
are long and colder. Yes, even the day seems as the night—all
darkness. Some around you seem to be enjoying perpetual spring-
time, because Christ shines so constantly upon their happy souls,
and your coldness and darkness seem all the sadder in contrast with
their warmth and brightness.
How can you account for this? Ask some Christian friends, and
they will tell you that you must not expect so much joy—that the
Christian life is a constant conflict with doubt and sin, and you
cannot expect to be always as happy as perhaps you were at first.
You turn away sadly disappointed. They are older Christians, and
you think they must know better than you. What will you do? Will
you sit under the clouds, or struggle to get out into clear sunshine?
We cannot think that God intends you to have a limited measure
of joy and peace. Why should you not grow happier in your love to
Christ as you learn to know him better? Why should not the
promises become more precious as you prove them and find them
all "yea and amen in Christ Jesus?"
Let us inquire into the cause of your darkness. The Saviour does
not willingly withhold his smile which makes spring and summer in
the soul. When God made a covenant with you he gave you this
promise: "I will never leave thee, nor forsake thee." God has not
then forsaken you. Perhaps you have neglected the means of grace.
Perhaps you are cherishing some secret sin. Perhaps you have
looked more to your own frames and feelings than to Christ's perfect
work. Your mind has dwelt too much upon self. Take the advice of
one who walked with God and was not, because God took him: "For
one look at self take ten looks to Christ." The advice is good, and it
has lifted many a Christian above the clouds.
"Saw ye Him whom my soul loveth? I sought him, but I found him
not." Is this your sad lament?

Seek him again. Seek him earnestly, prayerfully, constantly. Seek
him in the place of secret prayer. Jesus had his secret place upon the
lonely mountain. Though he lived in constant communion with his
Father, though his every step was a hymn of praise and his every act
was a prayer, still he felt his need of a place where he could pour out
his soul in supplication. If secret prayer was necessary for the
Master, is it not more needful for you? If you have neglected that, it
is not strange if it is winter in your soul.
Seek Jesus also in his holy word. In the garden of the gospel you
may meet him and walk with him, holding sweet communion. Here
he reveals himself. Obey his own commandment, "Search the
Scriptures." This is the reason and this the reward, "for they are they
that testify of me." They testify of Christ. Yes, they are full of Christ.
Rays from his cross shine through both the Testaments. Prophets
and saints of old looked forward and rejoiced—"not having received
the promises," it is true, "but having seen them afar off, and were
persuaded of them and embraced them." Fuller, clearer light now
shines on Calvary. Draw near and read again the sacred story. Yes,
"search the Scriptures," for here you will surely find Jesus. His love
prompted every promise, and is the pledge and fulfillment of every
promise.
Seek him in the place of social prayer. Thomas was not at the
prayer-meeting when Jesus manifested himself to his disciples. How
much he lost by staying away! When Jesus draws near and says,
"Peace be unto you!" then let me be within hearing of his gentle
voice. Let me be near when he says, "Receive ye the Holy Ghost."
"Only a prayer-meeting," do you say? Only a visit from Jesus, the
Giver of peace! Who would miss a visit of so much profit—a visit of
so much pleasure!
Seek Jesus at the sacramental supper. Jesus is there. There you
may enjoy his longest, sweetest visits. There he speaks peace to his
people. Sweet it is to meet Jesus in the closet; sweet visits there he
pays his beloved and betrothed. Sweet it is to meet him in the holy
Scriptures; sweet to find him in the place of social prayer. But

sweeter far are his visits at the communion-table. To sit like Mary at
his feet, to lie like John upon his bosom—was ever joy like this? was
ever Jesus nearer? No longer do we say, "Saw ye Him whom my soul
loveth?" We have found him! we have found him! "His left hand is
under my head, while his right doth embrace me." I charge you, my
unstable heart, that you forsake not, nor grieve again "Him whom
my soul loveth."
Now that you have found him, cleave to him. "Abide in me," the
Master says. In union with Christ the Christian finds his safety,
strength and happiness. And the closer this union, the greater is the
security, strength and happiness of the Christian. Would we be
guided by his eye? Then must we be continually "looking unto
Jesus." Do we need strength? "In the Lord Jehovah is everlasting
strength." Are we seeking happiness? "Happy is he that hath the
God of Jacob for his help, whose hope is in the Lord his God."
Cling closer, young Christian, cling closer to Christ. Learn to walk
with him daily in sweet communion. Be not satisfied with an
occasional visit from your Lord, but beseech him to abide with you.
He is willing to come and abide with you. "If any man love me, he
will keep my words: and my Father will love him, and we will come
unto him, and make our abode with him."

M
II.
His Name.
Y meditation of him shall be sweet when I remember his name.
We need not say, as did Jacob, "Tell me, I pray thee, thy
name." We know thy name, Jehovah Tsidkenu, "The Lord our
Righteousness." We are all as an unclean thing, and all our
righteousnesses are as filthy rags, and all the soap and nitre in the
world cannot make us pure and holy. "If I wash myself with snow-
water, and make my hands never so clean, yet shalt thou plunge me
in the ditch, and mine own clothes shall abhor me." But in the
covenant of the cross we come and change clothes with Christ. He
takes our filthy rags and gives us his own spotless robe; and we are
"accepted in the Beloved," not having our "own righteousness, which
is of the law, but that which is through the faith of Christ, the
righteousness which is of God by faith."
We know thy name, Jehovah Shalom, The Lord of Peace. Sweet
peace speedily follows as one of the results of justification. "And the
work of righteousness shall be peace, and the effects of
righteousness quietness and assurance for ever." Or, as the apostle
expresses it in the Epistle to the Romans, "Therefore, being justified
by faith, we have peace with God through our Lord Jesus Christ."
Peace was one of the notes in the song which angels sung when He
was born who himself "is our peace." And when he was parting from
his disciples "peace" was among the last words that fell from his lips:
"Peace I leave with you; my peace I give unto you." "Thou wilt keep
him in perfect peace whose mind is stayed on thee." "Perfect
peace," being interpreted, means, "Peace, peace." So that we shall
have a double portion, "good measure, pressed down and shaken
together and running over."

We know thy name, Jehovah Nissi, The Lord my Banner. "Thou
hast given a banner to them that fear thee." He his own self is our
standard and our standard-bearer, and we need not fear that our
flag shall ever be taken, or that those who fight under it shall be
beaten. Though we are but weak worms of the dust, and are called
to contend "against principalities, against powers, against spiritual
wickedness in high places," there is nothing more sure than that we
shall win the day. "If God be for us, who can be against us?" Looking
at the end from the beginning, and confident of victory, we can say,
when buckling on the harness before the battle is begun, "We are
more than conquerors through Him that loved us."
We know thy name, Jehovah Rophi, The Lord my Healer. When he
began his holy ministry here on earth, "Jesus went about all Galilee,
teaching in their synagogues, and preaching the gospel of the
kingdom, and healing all manner of sickness, and all manner of
disease among the people." Some came to him groping in their
blindness, others came on crutches, and many were carried to him
on their beds; and he healed them all. Though he came from heaven
mainly to heal diseases of the mind, yet while he labored here in the
flesh he healed more diseases of the body. He is still the only
Physician of the soul, and by far the best Physician of the body. "He
knoweth our frame," this our mortal body, better than the wisest
men, for he made it, and without his blessing the best prescription
will do us no good. He is our Physician. When we are taken sick he
is first called to our bedside. By prayer we lay hold of something at
the mercy-seat that rings a bell in heaven, and he makes haste and
comes down and "healeth all our diseases."
We know thy name, Jehovah Jireh, The Lord will Provide. He
provided a lamb upon Mount Moriah for Abraham in his greatest
emergency. He has also provided a Lamb for us—a Lamb without
spot or blemish, "the Lamb slain from the foundation of the world."
"Even Christ our Passover is sacrificed for us." On his guiltless head
our guilt was laid. And having provided a Lamb for us, he will
provide anything else. "My God shall supply all your need according
to his riches in glory by Christ Jesus." As the greater includes the

less, so the unspeakable gift embosoms all minor blessings. "He that
spared not his own Son, but delivered him up for us all, how shall he
not with him freely give us all things?"
We know thy name, Jehovah Shammah, The Lord is there.
Wherever we may be called to go, the Lord is there. What strong
consolation, what good cheer there is in this blessed truth,
"Awake, asleep, at home, abroad,
I am surrounded still with God!"
In every duty, in every difficulty, the Lord is there. In the lion's den
and in the fiery furnace, the Lord is there. In sickness and in health,
in sorrow and in joy, the Lord is there. When our pilgrimage is
almost over, and we are going down into the dark valley, blessed be
his name, we shall find that the Lord is there. "Yea, though I walk
through the valley of the shadow of death, I will fear no evil, for
thou art with me."
Beyond the valley there is a place about which we know very little;
but we know that there is a house of many mansions, and we know
that the Lord is there. "I go to prepare a place for you." There is a
holy city along whose golden streets these feet shall one day walk;
"And the name of the city from that day shall be, The Lord is there."
"Oh magnify the Lord with me, and let us exalt his name
together." He is everything to us. Are we sinners? He is our
Righteousness. Are we in trouble? He is our Peace. Are we soldiers?
He is our Banner. Are we sick? He is our Healer. Are we in want of
anything? He will provide. Are we going into eternity? He is there,
waiting to receive us up into glory. "Oh magnify the Lord with me,
and let us exalt his name together."
"My meditation of him shall be sweet" when I remember his
name, for "they that know thy name shall put their trust in thee."

M
III.
The Assurance.
Y meditation of him shall be sweet when I remember the
assurance he has given me.
To his dear children God is pleased to give earnests or pledges of
the future bliss. We cannot think that any of the heirs of glory are
wholly deprived of foretastes of heaven. Some indeed walk in the
mist-clouds of doubt for a great part of their lives. Only at intervals
the clouds part and reveal a ray of heavenly sunshine. They live
amid clouds—it may be they die amid clouds—and never know clear
shining until they reach the land of perpetual sunshine.
Others there are who pitch their tents upon "the high hill Clear."
They live in the land Beulah, where the sun is ever shining and the
birds are ever singing, where Giant Despair never comes and where
Doubting Castle is not so much as seen. They live in the sunshine,
they die in the sunshine—no, they do not die; they pass away,
onward and upward, into clearer light and brighter sunshine. Light is
sown for them on earth by Him who is the light of the world, and
the harvest in eternity is abundant and glorious. The first-fruits here,
though nothing compared with the after-fruits, are beautiful and
greatly to be desired. Why may they not be enjoyed by all?
We hardly think it is God's will that his children should have a
limited measure of peace and joy. Neither can we think it humility to
doubt the words of our Lord Jesus: "I give unto them eternal life;
and they shall never perish, neither shall any pluck them out of my
hand."
"Yes," we hear you saying, "this is comforting for Christians, but
am I a Christian? The clouds of unbelief often envelop me and

exclude all heavenly light. 'Whereby shall I know that I shall inherit
the land?' Who will assure me of my interest in Christ?"
"He that believeth on the Son of God hath the witness in himself."
Can you remain ignorant of so great a change wrought within by the
Spirit? Are there not many signs to prove to you that you are in
Christ? Do you not believe and know that a change has passed over
all your feelings and affections? Do you not love the things you once
hated and hate the things you once loved? Do you not love all who
bear the Saviour's image? Is not sin odious to you? Do you not find
some pleasure in drawing near to God in prayer? Is not the thought
of continuing in sin painful to you? Would you willingly grieve your
Saviour?
We would not say, "Peace! peace!" when there is no peace. We
would have you look well to the foundations of your hope. Examine
it closely. Let the light of the Word fall full and clear upon it. Look at
it on every side, and rest not till you know that it is founded simply
and solely upon the merits of the Redeemer. If you are sure Christ's
work is really begun in your soul, you need have no doubt about its
being continued and finally completed. The Master counts well the
cost when he begins his work in the sinner's soul, and none shall
ever mock his work, saying, "This man began to build and was not
able to finish."
Having ascertained this all-important fact, you may be "always
confident" till you enter his presence "with exceeding joy." You need
not fear that you shall fall away. "Rejoice not against me, O mine
enemy: when I fall, I shall arise." You shall be "kept by the power of
God through faith unto salvation." You need never fear that Christ
will weary of his work, but you may be "confident of this very thing,
that he which has begun a good work in you will perform it until the
day of Jesus Christ," and you shall stand "without fault before the
throne."
We know some humble and sincere disciples will shrink back,
saying, "We are not able," when we beg them to make Paul's
language all their own. With their hands upon their mouths and their

mouths in the dust, they dare not look up with perfect confidence;
they think it almost presumption, or at least they say, despondingly,
"It is not for me." "Paul," they say, "was an uncommon Christian—he
attained a tall stature in holiness." So he did; and why? Because his
was no half-way service; he gave no divided heart to his master.
That was the reason why he so well understood the doctrine of full
assurance. "If any man will do his will, he shall know of the
doctrine." Do you understand these words of the Master? He does
not say, "If any man fully keeps the law, which is the perfect will of
the Father, he shall know of the doctrine," for it is not possible for
any mere man perfectly to keep the commandments of God. Nor
does he say, "If any man does the will," but, "If any man will"—is
willing to do his will. If he shows a willing heart and mind, God will
enlighten him more and more. And what is implied in this willing
heart and mind but full consecration?
When shall we learn the secret of a happy life? "Ye cannot serve
two masters." Those who give themselves up to Satan's service may
lead an unhappy life, but greater must be the unhappiness of those
who are trying to make a compromise between God and Satan. They
can enjoy neither service; they are of all men most miserable.
O ye who have professed the name of Christ, come away from all
inferior pleasures! Pleasures? They are not worthy of the name. One
hour with Christ is worth them all. Will you then suffer them to hide
the Saviour from your view?
Once we were happy all the day long, having given ourselves to
Christ in the covenant of the cross. Christ was the source of our life,
the fullness of our joy, all our salvation and all our desire. Having
enjoyed his precious presence, we dreamed not that we could ever
wander; we thought our hearts would cleave to him for evermore.
We had no doubts in those days. "My Beloved is mine, and I am
his," was the constant language of our heart. But, alas! the world
again entered our heart, dividing it and leaving but half for God.
Then came the clouds gathering thick and fast, till our Saviour was
hidden from our view. Upon the ear of the watchman who went

about the streets soon fell our mournful cry, "Saw ye Him whom my
soul loveth?" We sought him, but we found him not. Our gloom and
grief increased. Oh for one hour of Jesus' presence! "Let all other
joys forsake this heart," we cried, "if only we may again enjoy Jesus'
presence." Feeling thus, we thrust the joys (falsely so called) of
earth away, and kneeling at the mercy-seat, we renewed our
covenant with Jesus. True, there was no joy in our hearts; we saw
not yet his smile. But we could trust him where we could not trace
him; so we confessed to him all our wanderings. We told him how
we had thought to serve him with half our hearts, but now we would
give him all. The first steps were taken in darkness, but God soon
revealed his smiling face.
If this assurance is attainable by one, why not by all? If at one
time it may be enjoyed, why not at all times? We have "for a
foundation a stone, a tried stone, a precious corner-stone, a sure
foundation," laid in Zion by the great Master-Builder.
Foundation-stones are chosen with great care and laid with care,
for upon them the whole building depends. Look at this foundation-
stone. Tell me, is it not perfect, sure and tried? This is the stone that
the builders rejected: they perished, but it remaineth, and upon it
the Lord hath built his Church. Believers in all ages and climes have
built all their hopes of heaven upon it. Is it not a tried stone? Satan
tried it and found no flaw; Pilate tried it and found no fault; the
Father tried it and pronounced it good; and we have tried it and
proved it so. What a sure foundation it is, with Christ for the corner-
stone, the next stone faith, then repentance, hope, submission and
all the graces! "Master, see what manner of stones are here." Are
they not goodly stones? and will they not make a beautiful temple?
Upon Christ, the precious corner-stone, let us build our hopes of
heaven, and dismiss all fears for the future.
My hope, my joy, my salvation, my desire, my righteousness, my
strength, my all—Christ in me "the hope of glory." "Lord, who shall
abide in thy tabernacle? who shall dwell in thy holy hill?" I have not
clean hands, nor a pure heart. Behold, I am vile. Nevertheless, I

shall abide in thy tabernacle; I shall dwell in thy holy hill. Why?
Because Christ is mine. His hands are spotless, his heart is pure, his
righteousness is perfect. All his is mine, for he is mine. I build my
hopes upon the Rock Christ Jesus. These hopes shall never be
overthrown; I have no fear of it.
When the head stone shall be placed I cannot tell, but I wait and
work with joy, hoping unto the end. Sometimes weariness almost
overcomes me, for building is hard work. Foes within and foes
without make the labor exceedingly hard. But whether in joy or grief,
the building goes on, and from the completed structure shouts shall
ascend to the great Master-Builder: "Grace, grace unto it!" "Glory be
to the Father, and to the Son, and to the Holy Ghost! Amen."

M
IV.
The Perfect Work.
Y meditation of him shall be sweet when I consider his perfect
work.
What consternation must have been felt among the ranks of holy
spirits when sin entered into the world, "and death by sin!" Could
grief intrude into heaven, we should imagine that an hour of deepest
anguish when the Father, looking down upon the fallen race,
exclaimed, "How shall I pardon thee for this?" "How shall I put thee
among the children?" How could the just and holy God justify the
sinner? Not one of all the heavenly host could solve the problem.
"How shall I give thee up?" burst from the heart of the loving Father.
The beloved Son exclaims: "Deliver him from going down to the pit;
I have found a ransom." "Who will seek and save these wanderers?"
says the Father. "Father, send me," the Son replies; "I will seek
them, and save them, and bring them home. I will bear the wrath
due to them for sin; I will die for them." The Father accepts the
Substitute; the Son lays aside his glory and girds himself for the
mighty conflict. He looks along the line of weary years, and though
he sees nothing but suffering, reproach and death, his holy purpose
remains unshaken. The lost sheep of the house of Israel must be
saved, and none but Jesus could save them.
"So he was their Saviour."
His work of justification is perfect. Look at it for a moment. What
is justification? "Justification is an act of God's free grace, wherein
he pardoneth all our sins, and accepteth us as righteous in his sight,
only for the righteousness of Christ imputed to us, and received by
faith alone."

Can there be anything more simple and beautiful and perfect than
this? It is free to all; it is sufficient for all: "Whosoever will;" "And I
will pardon all their iniquities." It is the work of a moment, but it
abideth for ever. One look of faith, and life, eternal life, is yours.
"The moment a sinner believes
And trusts in his crucified Lord,
His pardon at once he receives,
Redemption in full through his blood."
His work of adoption is perfect. Like justification, it is done in a
moment, and it abideth for ever. "Adoption is an act of God's free
grace, whereby we are received into the number and have a right to
all the privileges of the sons of God."
The Romans had a twofold form of adoption. The first was a
private transaction between the parties, receiving the person
adopted into the family; the second was the public recognition in the
forum.
The moment we are justified we are adopted. This is the private
transaction. Hearing a voice from heaven saying, "Thy sins are
forgiven thee; go in peace," we look up through our tears, and with
rejoicing lips we cry, "Father!" "Now are we sons of God," placed
among the children, because Jesus solved the mighty problem,
showing how God can be just and yet justify the sinner. The public
recognition will come very soon. When we reach the pearly gates,
Jesus, our Elder Brother, will be waiting to receive and acknowledge
us as his own. Standing before his Father and ours, he will stretch
forth his hand toward his disciples and say, "Behold my mother and
my brethren!"
His work of sanctification is perfect. It is not, like justification and
adoption, an act done in a moment. It is a work slow and at times
painful, yet sure and perfect. It begins when we are justified, it ends
when we are glorified. "Sanctification is the work of God's free
grace, whereby we are renewed in the whole man after the image of
God, and are enabled more and more to die unto sin and live unto

righteousness." It is often a painful work. "The flesh, with the
affections and lusts," must be crucified. We must "die unto sin." The
sound of the hammer and axe and iron tools is not heard by those
who are without, yet every blow causes the heart to quiver, and the
cutting is very painful. Nevertheless, who would not be "a carved
stone" in the temple of our God?
We praise thee for this work, O God. We rejoice to know that thou
wilt not weary of it, but wilt carry it on "until the day of Jesus
Christ." We shall be perfect in that day. No imperfection shall remain
in us—no sinful desire, no unholy thought. Jesus will say unto us,
"Thou art all fair, my love; there is no spot in thee," and he will
present us "faultless before the presence of his glory with exceeding
joy."
His work of redemption is perfect. Christ, our Prophet, instructs
us, "revealing to us, by his word and Spirit, the will of God for our
salvation." Christ, our Priest, offers up himself "a sacrifice to satisfy
divine justice and reconcile us to God." He also "maketh continual
intercession for us." Christ, our King, subdues "us to himself;" he
rules and defends us, and restrains and conquers "all his and our
enemies." Is he not a perfect Redeemer? He redeems our souls from
death, our bodies also from the grave. "My flesh also shall rest in
hope," always confident of a glorious resurrection. "For I know that
my Redeemer liveth, and that he shall stand at the latter day upon
the earth; and though after my skin worms destroy this body, yet in
my flesh shall I see God." "I will ransom them from the power of the
grave; I will redeem them from death. O Death, I will be thy plague!
O Grave, I will be thy destruction!"
Though some may cavil at this mystery and say sneeringly, "How
are the dead raised up? and with what body do they come?" yet we
trust in the word of our God, and "we know that if our earthly house
of this tabernacle were dissolved, we have a building of God, an
house not made with hands, eternal in the heavens." Christ, "the
first-fruits of them that slept," is risen; then how say some among
you that there is no resurrection of the dead? "Christ is risen!" Oh

glorious truth, first proclaimed to the women who came weeping to
his sepulchre! "Fear ye not," the angel answered, "for I know that ye
seek Jesus which was crucified. He is not here; for he is risen, as he
said." Christ is risen! Then we which are Christ's shall rise also.
"Because I live ye shall live also." "Behold, I show you a mystery:"
"the dead shall be raised incorruptible, and we shall be changed. For
this corruptible must put on incorruption, and this mortal must put
on immortality."
O Lord, our Redeemer, Prophet, Priest and King, we praise thee
for thy perfect work!
Yes, "my meditation of him shall be sweet" when I consider his
perfect work. My Master too regards it with satisfaction; he sees of
the travail of his soul, and is satisfied. His life on earth was
sorrowful, but his triumph was complete. "Having spoiled
principalities and powers," God's enemies and ours, "he made a
show of them openly, triumphing over them in it," or in himself, as it
may be rendered. As a victor returning from the fight, he ascended
to the glory which he had with the Father "before the world was;"
and the song of the glorified filled the high heavens with richer
harmony as the Well-Beloved of the Father proved by the nail-prints
that he had finished the work which was given him to do.
Coming ages will testify to his triumph and to the completeness of
his work. On earth it was for the most part viewed not only with
indifference, but even with unbelief and scorn. "He came unto his
own, and his own received him not." "For a good work we stone
thee not; but for blasphemy, and because that thou, being a man,
makest thyself God." "He saved others; let him save himself, if he be
Christ, the chosen of God." "If thou be Christ, save thyself and us."
"If he be the King of Israel, let him now come down from the cross,
and we will believe him." But now a mighty multitude swell the song,
"Worthy is the Lamb that was slain, to receive power, and riches,
and wisdom, and strength, and honor, and glory, and blessing. And
every creature which is in heaven, and on the earth, and such as are
in the sea, and all that are in them, heard I saying, Blessing, and

honor, and glory, and power, be unto Him that sitteth upon the
throne, and unto the Lamb, for ever and ever. And the four beasts
said, Amen. And the four and twenty elders fell down and worshiped
Him that liveth for ever and ever."
"Ten thousand times ten thousand sung
Loud anthems round the throne,
When lo! one solitary tongue
Began a song unknown—
A song unknown to angel ears—
A song that told of banished fears,
Of pardoned sins and dried up tears.
"Not one of all the heavenly host
Could these high notes attain,
But spirits from a distant coast
United in the strain;
Till he who first began the song,
To sing alone not suffered long,
Was mingled with a countless throng.
"And still, as hours are fleeting by,
The angels ever bear
Some newly-ransomed soul on high
To join the chorus there:
And so the song will louder grow,
Till all redeemed by Christ below
To that fair world of rapture go.
"Oh give me, Lord, my golden harp,
And tune my broken voice,
That I may sing of troubles sharp
Exchanged for endless joys:
The song that ne'er was heard before—
A sinner reached the heavenly shore—
But now shall sound for evermore."

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