It is the supreme art of the teacher to awaken joy in creative expression and knowledge.

Time is relative; its only worth depends upon what we do as it is passing.

This is too difficult for a mathematician. It takes a philosopher. The hardest thing in the world to understand is the income tax.

A knowledge of the existence of something we cannot penetrate, of the manifestations of the profoundest reason and the most radiant beauty - it is this knowledge and this emotion that constitute the truly religious attitude; in this sense, and in this alone, I am a deeply religious man.

[Mystery] is the fundamental emotion that stands at the cradle of true art and true science.

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.

To invent something, all you need is imagination and a big pile of junk.