Man is, at one and the same time, a solitary being and a social being.

Concern for man and his fate must always form the chief interest of all technical endeavors. Never forget this in the midst of your diagrams and equations.

It is open to every man to choose the direction of his striving; and also every man may draw comfort from Lessing's fine saying, that the search for truth is more precious than its possession.

Three great forces rule the world: stupidity, fear and greed.

What can the schools do to defend democracy? Should they preach a specific political doctrine? I believe they should not. If they are able to teach young people to have a critical mind and a socially oriented attitude, they will have done all that is necessary.

As far as the laws of mathematics refer to reality, they are not certain, and as far as they are certain, they do not refer to reality.

In every true searcher of Nature there is a kind of religious reverence, for he finds it impossible to imagine that he is the first to have thought out the exceedingly delicate threads that connect his perceptions