Oh God, how do the world and heavens confine themselves, when our hearts tremble in their own barriers!

What I possess, seems far away to me, and what is gone becomes reality.

Ill-humor is nothing more than an inward feeling of our own want of merit, a dissatisfaction with ourselves which is always united with an envy that foolish vanity excites.

First and last, what is demanded of genius is love of truth.

Mathematicians are like Frenchmen: whatever you say to them they translate into their own language and forthwith it is something entirely different.

Tolerance should really be only a temporary attitude; it must lead to recognition. To tolerate means to offend.

Nature! We live in her midst and know her not. She is incessantly speaking to us, but betrays not her secret. We constantly act upon her, and yet have no power over her. Variant: NATURE! We are surrounded and embraced by her: powerless to separate ourselves from her, and powerless to penetrate beyond her.