All the scientist creates in a fact is the language in which he enunciates it. If he predicts a fact, he will employ this language, and for all those who can speak and understand it, his prediction is free from ambiguity. Moreover, this prediction once made, it evidently does not depend upon him whether it is fulfilled or not.

It is not order only, but unexpected order, that has value.

It is with logic that one proves; it is with intuition that one invents.

If nature were not beautiful, it would not be worth knowing, and if nature were not worth knowing, life would not be worth living

Geometry is not true, it is advantageous.

Most striking at first is the appearance of sudden illumination, a manifest sign of long unconscious prior work.

Analyse data just so far as to obtain simplicity and no further.