No fairer destiny could be allotted to any physical theory than that it should of itself point out the way to the introduction of a more comprehensive theory, in which it lives on as a limiting case.

For an idea which, at first, does not seem absurd, there is no hope.

If you can't explain something simply, you don't know enough about it.

I simply imagine it so, then go about to prove it.

Out of the multitude of our sense experiences we take, mentally and arbitrarily, certain repeatedly occurring complexes of sense impression (partly in conjunction with sense impressions which are interpreted as signs for sense experiences of others), and we attribute to them a meaning the meaning of the bodily object.

We know nothing at all. All our knowledge is but the knowledge of schoolchildren. The real nature of things we shall never know.

Isn't it strange that I who have written only unpopular books should be such a popular fellow?