The schematicism by which our understanding deals with the phenomenal world ... is a skill so deeply hidden in the human soul that we shall hardly guess the secret trick that Nature here employs.

Two things strike me dumb: the infinite starry heavens, and the sense of right and wrong in man.

The question is not so much whether there is life on Mars as whether it will continue to be possible to live on Earth

If man makes himself a worm he must not complain when he is trodden on.

Seek not the favor of the multitude; it is seldom got by honest and lawful means. But seek the testimony of few; and number not voices, but weigh them.

I feel a complete thirst for knowledge and an eager unrest to go further in it as well as satisfaction at every acquisition. There was a time when I believed that this alone could constitute the honor of mankind, and I had contempt for the ignorant rabble who know nothing.

Rules for Happiness: something to do, someone to love, something to hope for.