A man is a poet if difficulties inherent in his art provide him with ideas; he is not a poet if they deprive him of ideas.

Liberty is the hardest test that one can inflict on a people. To know how to be free is not given equally to all men and all nations.

What is simple is wrong, and what is complicated cannot be understood.

It would be impossible to "love" anyone or anything one knew completely. Love is directed towards what lies hidden in its object.

The purpose of psychology is to give us a completely different idea of the things we know best.

The great virtues of the German people have created more evils than idleness ever did vices

Science is feasible when the variables are few and can be enumerated; when their combinations are distinct and clear. We are tending toward the condition of science and aspiring to do it. The artist works out his own formulas; the interest of science lies in the art of making science.