With all my heart I believe that the world's present system of sovereign nations can only lead to barbarism, war and inhumanity, and that only world law can assure progress towards a civilized peaceful community.

It is best, it seems to me, to separate one's inner striving from one's trade as far as possible. It is not good when one's daily break is tied to God's special blessing.

A scientist is a mimosa when he himself has made a mistake, and a roaring lion when he discovers a mistake of others.

I don't try to imagine a personal God; it suffices to stand in awe at the structure of the world, insofar as it allows our inadequate senses to appreciate it.

(Reply on what constitutes scientific proof:)"The question is much too difficult for me.

One of the strongest motives that lead men to art and science is escape from everyday life with its painful crudity and hopeless dreariness, from the fetters of one's own ever-shifting desires. A finely tempered nature longs to escape from the personal life into the world of objective perception and thought.

By academic freedom I understand the right to search for truth and to publish and teach what one holds to be true. This right also implies a duty: one must not conceal any part of what one has recognized to be true.