A powerful idea communicates some of its strength to him who challenges it.

But sometimes illumination comes to our rescue at the very moment when all seems lost; we have knocked at every door and they open on nothing until, at last, we stumble unconsciously against the only one through which we can enter the kingdom we have sought in vain a hundred years - and it opens.

The heart changes...but we learn of it only from reading or by imagination; for in reality its alteration, like that of certain natural phenomena, is so gradual that, even if we are able to distinguish, successively, each of its different states, we are still spared the actual sensation of change.

Similarly the men who produce works of genius are not those who live in the most delicate atmosphere, whose conversation is most brilliant, or their culture broadest, but those who have had the power, ceasing in a moment to live only for themselves, to make use of their personality as of a mirror.

There is no doubt that a person's charms are less frequently a cause of love than a remark such as: 'No, this evening I shan't be free'.

In a language known to us, we have substituted the opacity of the sounds with the transparence of the ideas. But a language we donot know is a closed place in which the one we love can deceive us, making us, locked outside and convulsed in our impotence, incapable of seeing or preventing anything.

Any mental activity is easy if it need not be subjected to reality.