The purpose of abstraction is not to be vague, but to create a new semantic level in which one can be absolutely precise.

LISP has jokingly been described as "the most intelligent way to misuse a computer." I think that description is a great compliment because it transmits the full flavour of liberation: it has assisted a number of our most gifted fellow humans in thinking previously impossible thoughts.

I now have had my foggy crystal ball for quite a long time. Its predictions are invariably gloomy and usually correct, but I am quite used to that and they won't keep me from giving you a few suggestions, even if it is merely an exercise in futility whose only effect is to make you feel guilty.

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

In this respect a program is like a poem: you cannot write a poem without writing it. Yet people talk about programming as if it were a production process and measure "programmer productivity" in terms of "number of lines of code produced". In so doing they book that number on the wrong side of the ledger: we should always refer to "the number of lines of code spent".

...Simplifications have had a much greater long-range scientific impact than individual feats of ingenuity. The opportunity for simplification is very encouraging, because in all examples that come to mind the simple and elegant systems tend to be easier and faster to design and get right, more efficient in execution, and much more reliable than the more contrived contraptions that have to be debugged into some degree of acceptability....Simplicity and elegance are unpopular because they require hard work and discipline to achieve and education to be appreciated.

Write a paper promising salvation, make it a "structured" something or a "virtual" something, or "abstract," "distributed" or "higher-order" or "applicative" and you can almost be certain of having started a new cult.