Professors typically spend their time in meetings about planning, policy, proposals, fund-raising, consulting, interviewing, traveling, and so forth, but spend relatively little time at their drawing boards. As a result, they lose touch with the substance of their rapidly developing subject. They lose the ability to design; they lose sight of what is essential; and they resign themselves to teach academically challenging puzzles.

But active programming consists of the design of new programs, rather than contemplation of old programs.

I have never designed a language for its own sake.

Software is getting slower more rapidly than hardware becomes faster.

During the process of stepwise refinement, a notation which is natural to the problem in hand should be used as long as possible.

Experience shows that the success of a programming course critically depends on the choice of these examples.

Our ultimate goal is extensible programming. By this, we mean the construction of hierarchies of modules, each module adding new functionality to the system.