We must prefer real hell to an imaginary paradise.

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.

To be a hero or a heroine, one must give an order to oneself.

When war is waged, it is for the purpose of safeguarding or increasing one's capacity to make war. International politics are wholly involved in this vicious cycle. What is called national prestige consists in behaving always in such a way as to demoralize other nations by giving them the impression that, if it comes to war, one would certainly defeat them. What is called national security is an imaginary state of affairs in which one would retain the capacity to make war while depriving all other countries of it.

Those who love a cause are those who love the life which has to be led in order to serve it.

One does not play Bach without having done scales. But neither does one play a scale merely for the sake of the scale.

The payment of debts is necessary for social order. The non-payment is quite equally necessary for social order. For centuries humanity has oscillated, serenely unaware, between these two contradictory necessities.