It is a law of nature that we defend ourselves from one affection only by means of another.

History justifies whatever we want it to. It teaches absolutely nothing, for it contains everything and gives examples of everything.

Growing nations should remember that, in nature, no tree, though placed in the best conditions of light, soil, and plot, can continue to grow and spread indefinitely.

The purpose of psychology is to give us a completely different idea of the things we know best.

The mere notion of photography, when we introduce it into our meditation on the genesis of historical knowledge and its true value, suggests the simple question: Could such and such a fact, as it is narrated here, have been photographed?

The future, like everything else, is no longer quite what it used to be.

Ignorance is a treasure of infinite price that most men squander, when they should cherish its least fragments; some ruin it by educating themselves, others, unable to so much as conceive of making use of it, let it waste away. Quite on the contrary, we should search for it assiduously in what we think we know best. Leaf through a dictionary or try to make one, and you will find that every word covers and masks a well so bottomless that the questions you toss into it arouse no more than an echo.