Make everything as simple as possible, but not simpler.

I think we have to safeguard ourselves against people who are a menace to others, quite apart from what may have motivated their deeds.

A forced faithfulness is a bitter fruit for all concerned.

The payment of the worker is not determined by the value of his product.

Fantasie is belangrijker dan kennis, want kennis is begrensd.

It is important to foster individuality, for only the individual can produce the new ideas.

It is a very grave mistake to think that the enjoyment of seeing and searching can be promoted by means of coercion and a sense of duty. To the contrary, I believe it would be possible to rob even a healthy beast of prey of its voraciousness, if it were possible, with the aid of a whip, to force the beast to devour continuously, even when not hungry.