John von Neumann draws attention to what seemed to him a contrast. He remarked that for simple mechanisms, it is often easier to describe how they work than what they do, while for more complicated mechanisms, it is usually the other way around.

In the good old days physicists repeated each other's experiments, just to be sure. Today they stick to FORTRAN, so that they can share each other's programs, bugs included.

FORTRAN, the infantile disorder, by now nearly 20 years old, is hopelessly inadequate for whatever computer application you have in mind today: it is now too clumsy, too risky, and too expensive to use.

The effective exploitation of his powers of abstraction must be regarded as one of the most vital activities of a competent programmer.

Beware of "the real world". A speaker's apeal to it is always an invitation not to challenge his tacit assumptions.

Teaching to unsuspecting youngsters the effective use of formal methods is one of the joys of life because it is so extremely rewarding.

A most important, but also most elusive, aspect of any tool is its influence on the habits of those who train themselves in its use. If the tool is a programming language this influence is, whether we like it or not, an influence on our thinking habits.... A programming language is a tool that has profound influence on our thinking habits.