All the knowledge I possess everyone else can acquire, but my heart is all my own.

When I consider the narrow limits within which our active and inquiring faculties are confined; when I see how all our energies are wasted in providing for mere necessities, which again have no further end than to prolong a wretched existence; and then that all our satisfaction concerning certain subjects of investigation ends in nothing better than a passive resignation... when I consider all this... I am silent.

Three things are to be looked to in a building: that it stand on the right spot; that it is securely founded; that it be successfully executed.

A useless life is an early death.

No one would talk much in society if they knew how often they misunderstood others.

Please send me your last pair of shoes, worn out with dancing as you mentioned in your letter, so that I might have something to press against my heart.

Normally, the sciences distance themselves from life and the return to it via a detour.