It is only men who are free, who create the inventions and intellectual works which to us moderns make life worth while.

Each act is an island in time, to be judged on its own.

Overemphasis of the competitive system and premature specialization on the ground of immediate usefulness kill the spirit on which all cultural life depends, specialized knowledge included.

What physics looks for: The simplest possible system of thought which will bind together the observed facts.

How can he possibly be humble? He hasn't done anything yet.

If one day you have to choose between the world and love, remember this: If you choose the world you’ll be left without love, but if you choose love, with it you will conquer the world

All the fifty years of conscious brooding have brought me no closer to answer the question, "What are light quanta?" Of course today every rascal thinks he knows the answer, but he is deluding himself.