One must marry one's feelings to one's beliefs and ideas. That is probably the only way to achieve a measure of harmony in one's life.

There could be no fairer destiny for any physical theory than that it should point the way to a more comprehensive theory in which it lives on as a limiting case.

The doors of wisdom are never shut.

Big results require big ambitions.

What happens at 50, more or less, you lose what you need to create another person, to sustain another person; you keep what you need to sustain yourself. And there's something wonderful about that.