It is necessary for the very existence of science that minds exist which do not allow that nature must satisfy some preconceived conditions.

If you thought you were trying to find out more about it because you're gonna get an answer to some deep philosophical question...you may be wrong! It may be that you can't get an answer to that particular question by finding out more about the character of nature. But my interest in science is to simply find out about the world.

People may come along and argue philosophically that they like one better than another; but we have learned from much experience that all philosophical intuitions about what nature is going to do fail.

We need to teach how doubt is not to be feared but welcomed. It's OK to say, "I don't know."

All theoretical chemistry is really physics; and all theoretical chemists know it.

We have this terrible struggle to try to explain things to people who have no reason to want to know.

A scientist is never certain. ... We absolutely must leave room for doubt or there is no progress and there is no learning.