"Design bugs are often subtle and occur by evolution with early assumptions being forgotten as new features or uses are added to systems."

“The computer field is intoxicated with change. We have seen galloping growth over a period of four decades and it still does not seem to be slowing down. The field is not mature yet and already it accounts for a significant percentage of the Gross National Product.”

“It is important to emphasize the value of simplicity and elegance, for complexity has a way of compounding difficulties and as we have seen, creating mistakes. My definition of elegance is the achievement of a given functionality with a minimum of mechanism and a maximum of clarity.”

“The value of metaphors should not be underestimated. Metaphors have the virtue of an expected behavior that is understood by all. Unnecessary communication and misunderstandings are reduced. Learning and education are quicker. In effect metaphors are a way of internalizing and abstracting concepts allowing one's thinking to be on a higher plane and low-level mistakes to be avoided.”

“One is faced with a dilemma: If one places total trust in all other users, one is vulnerable to the antisocial behavior of any malicious user—consider the case of viruses. But if one tries to be totally reclusive and isolated, one is not only bored, but one's information universe will cease to grow and be enhanced by interaction with others. The result is that most of us operate in a complicated trade-off zone with various arrangements of trust and security mechanisms.”

“Regardless of whether one is dealing with assembly language or compiler language, the number of debugged lines of source code per day is about the same!”

“Clearly, one can obfuscate one's ideas with a compiler language but it's harder. To some extent one is talking about what one wants rather than how one wants to do it. The trouble with machine code, of course, is that when you look at a random section of machine code you don't know what properties of the instructions the programmer really wanted to exploit.”