Today's brains are yesterday's mashed potatoes.

I don't have to be good because they think I'm going to be good.

Scientific knowledge is a body of statements of varying degrees of certainty -- some most unsure, some nearly sure, none absolutely certain.

We've learned from experience that the truth will out.

People who wish to analyze nature without using mathematics must settle for a reduced understanding.

The first principle is that you must not fool yourself and you are the easiest person to fool.

When a Caltech student asked the eminent cosmologist Michael Turner what his "bias" was in favoring one or another particle as a likely candidate to compromise dark matter in the universe, Feynmann snapped, "Why do you want to know his bias? Form your own bias!"