Bodies do not produce sensations, but complexes of elements (complexes of sensations) make up bodies.

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.

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

The fact is, every thinker, every philosopher, the moment he is forced to abandon his one-sided intellectual occupation by practical necessity, immediately returns to the general point of view of mankind.

Bodies do not produce sensations, but complexes of elements (complexes of sensations) make up bodies.

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.

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.