Learning without thought is labor lost.

On being asked what he meant by the beauty of a mathematical theory of physics, Dirac replied that if the questioner was a mathematician then he did not need to be told, but were he not a mathematician then nothing would be able to convince him of it.

Man is not born to solve the problems fo the universe, but to find out where the problems begin, and then to take his stand witin the limits of the intelligible.

Science is organized knowledge. Wisdom is organized life.

What we see depends mainly on what we look for.

He who knows does not speak. He who speaks does not know. Close the mouth.

By doubting we come at truth.

An independent reality in the ordinary physical sense can ... neither be ascribed to the phenomena nor to the agencies of observation.

Everything is vague to a degree you do not realize till you have tried to make it precise.

A scholar who cherishes the love of comfort is not fit to be deemed a scholar.