The whole thing that makes a mathematician’s life worthwhile is that he gets the grudging admiration of three or four colleagues.

Programming is the art of telling another human being what one wants the computer to do.

TeX has found at least one bug in every Pascal compiler it's been run on, I think, and at least two in every C compiler

The hardest thing is to go to sleep at night, when there are so many urgent things needing to be done. A huge gap exists between what we know is possible with today's machines and what we have so far been able to finish.

These machines have no common sense; they have not yet learned to "think," and they do exactly as they are told, no more and no less. This fact is the hardest concept to grasp when one first tries to use a computer.

The sun comes up just about as often as it goes down, in the long run, but this doesn't make its motion random.

We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil.