We cannot define anything precisely. If we attempt to, we get into the paralysis of thought that comes to philosophers, who sit opposite each other, one saying to the other, "You don't know what you are talking about!" The second one says, "What do you mean by know? What do you mean by talking? What do you mean by you?"

If it disagrees with experiment, it's wrong.

Thank you very Much, I enjoyed myself

You see, I get such fun out of thinking that I don't want to destroy this most pleasant machine that makes life such a big kick.

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.

The problem of creating something new, but which is consistent with everything which has been seen before, is one of extreme difficulty.

Observation, reason, and experiment make up what we call the scientific method.