A movement that we will to execute is never more than a represented movement, and appears in a different domain from that of the executed movement, which always takes place when the image is vivid enough.

I can accept the theory of relativity as little as I can accept the existence of atoms and other such dogmas.

Strange as it may sound, the power of mathematics rests on its evasion of all unnecessary thought and on its wonderful saving of mental operations.

Many an article that I myself penned twenty years ago impresses me now as something quite foreign to myself.

The mathematician who pursues his studies without clear views of this matter, must often have the uncomfortable feeling that his paper and pencil surpass him in intelligence.

A colour is a physical object as soon as we consider its dependence, for instance, upon its luminous source, upon other colours, upon temperatures, upon spaces, and so forth.

If our dreams were more regular, more connected, more stable, they would also have more practical importance for us.