My internal and external life depend so much on the work of others that I must make an extreme effort to give as much as I receive.

If a man aspires towards a righteous life, his first act of abstinence is from injury to animals.

Even though the realms of religion and science in themselves are clearly marked off from each other, nevertheless there exist between the two strong reciprocal relationships and dependencies.

In two weeks the sheeplike masses of any country can be worked up by the newspapers into such a state of excited fury that men are prepared to put on uniforms and kill and be killed, for the sake of the sordid ends of a few interested parties. Compulsory military service seems to me the most disgraceful symptom of that deficiency in personal dignity from which civilized mankind is suffering today.

But there is another reason for the high repute of mathematics: it is mathematics that offers the exact natural sciences a certain measure of security which, without mathematics, they could not attain.

The series of integers is obviously an invention of the human mind, a self-created tool which simplifies the ordering of certain sensory experiences.

Most people say that it is the intellect which makes a great scientist. They are wrong: it is character.