Some people think Wheeler's gotten crazy in his later years, but he's always been crazy.

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

Our freedom to doubt was born out of a struggle against authority in the early days of science. It was a very deep and strong struggle: permit us to question - to doubt - to not be sure. I think that it is important that we do not forget this struggle and thus perhaps lose what we have gained.

There are all kinds of interesting questions that come from a knowledge of science, which only adds to the excitement and mystery and awe of a flower.

Outside of their particular area of expertise scientists are just as dumb as the next person.

You can’t say A is made of B or vice versa. All mass is interaction.

The exception tests the rule.