Despite my being an old gypsy there is a tendency to respectability inherent in old age.

A theory is the more impressive the greater is the simplicity of its premises, the more different are the kinds of things it relates and the more extended the range of its applicability.

The opinion prevailed among advanced minds that it was time that belief should be replaced increasingly by knowledge; belief that did not itself rest on knowledge was superstition, and as such had to be opposed.

When I have one week to solve a seemingly impossible problem, I spend six days defining the problem. Then, the solution becomes obvious.

You can't use an old map to explore a new world.

The more success the quantum theory has, the sillier it looks

Strive not to be a success, but rather to be of value.