A list is only as strong as its weakest link.

If you optimize everything, you will always be unhappy.

Always remember, however, that there’s usually a simpler and better way to do something than the first way that pops into your head.

The best theory is inspired by practice.

I've never been a good estimator of how long things are going to take.

...One of the most important lessons, perhaps, is the fact that SOFTWARE IS HARD. From now on I shall have significantly greater respect for every successful software tool that I encounter. During the past decade I was surprised to learn that the writing of programs for TeX and Metafont proved to be much more difficult than all the other things I had done (like proving theorems or writing books). The creation of good software demand a significiantly higher standard of accuracy than those other things do, and it requires a longer attention span than other intellectual tasks.

Science is knowledge which we understand so well that we can teach it to a computer; and if we don't fully understand something, it is an art to deal with it.