To receive applause for works which do not demand all our powers hinders our advance towards a perfecting of our spirit. It usually means that thereafter we stand still.

With a pen in my hand I have successfully stormed bulwarks from which others armed with sword and excommunication have been repulsed.

Astronomy is perhaps the science whose discoveries owe least to chance, in which human understanding appears in its whole magnitude, and through which man can best learn how small he is.

All mathematical laws which we find in Nature are always suspect to me, in spite of their beauty. They give me no pleasure. They are merely auxiliaries. At close range it is all not true.

Erudition can produce foliage without bearing fruit.

There were honest people long before there were Christians and there are, God be praised, still honest people where there are no Christians. It could therefore easily be possible that people are Christians because true Christianity corresponds to what they would have been even if Christianity did not exist.

One has to do something new in order to see something new.