We have to believe that everything has a cause, as the spider spins its web in order to catch flies. But it does this before it knows there are such things as flies.

If people should ever start to do only what is necessary millions would die of hunger.

What a blessing it would be if we could open and shut our ears...as easily as we open and shut our eyes.

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.

So-called professional mathematicians have, in their reliance on the relative incapacity of the rest of mankind, acquired for themselves a reputation for profundity very similar to the reputation for sanctity possessed by theologians.

The Greeks possessed a knowledge of human nature we seem hardly able to attain to without passing through the strengthening hibernation of a new barbarism.

Virtue by premeditation isn't worth much.