Difficult as it is really to listen to someone in affliction, it is just as difficult for him to know that compassion is listening to him.

To wish to escape from solitude is cowardice. Friendship is not to be sought, not to be dreamed, not to be desired; it is to be exercised (it is a virtue).

It is not through the way in which someone speaks about God that I can see whether that person has passed through the crucible of Divine Love, but through the way the person speaks to me about things here on earth.

We should do only those righteous actions which we cannot stop ourselves from doing.

Mathematics alone make us feel the limits of our intelligence. For we can always suppose in the case of an experiment that it is inexplicable because we don't happen to have all the data. In mathematics we have all the data, brought together in the full light of demonstration, and yet we don't understand. We always come back to the contemplation of our human wretchedness. What force is in relation to our will, the impenetrable opacity of mathematics is in relation to our intelligence.

Every kind of reward constitutes a degradation of energy.

Love: To feel with one's whole self the existence of another being.