The electron is a theory. But the theory is so good we can almost consider them real.

Everybody who reasons carefully about anything is making a contribution ... and if you abstract it away and send it to the Department of Mathematics they put it in books.

There's plenty of room at the bottom.

To those who do not know mathematics it is difficult to get across a real feeling as to the beauty, the deepest beauty, of nature ... If you want to learn about nature, to appreciate nature, it is necessary to understand the language that she speaks in.

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.

To decide upon the answer is not scientific. In order to make progress, one must leave the door to the unknown ajar ajar only.

Know your place in the world and evaluate yourself fairly, not in terms of the naïve ideals of your own youth, nor in terms of what you erroneously imagine your teacher's ideals are.