Nothing truly valuable arises from ambition or from a mere sense of duty; it stems rather from love and devotion towards men and towards objective things.

The goal of pacifism is possible only though a supranational organization. To stand unconditionally for this cause is the criterion of true pacifism.

If we knew what it was we were doing, it would not be called research, would it?

Academic chairs are many, but wise and noble teachers are few; lecture-rooms are numerous and large, but the number of young people who genuinely thirst after truth and justice is small

No fairer destiny could be allotted to any physical theory than that it should of itself point out the way to the introduction of a more comprehensive theory, in which it lives on as a limiting case.

I have tried 99 times and have failed, but on the 100th time came success.

War cannot be humanized. It can only be abolished.