Never lend books, for no one ever returns them; the only books I have in my library are books that other folks have left me.
Existence would be intolerable if we were never to dream.
It's not by amusing oneself that one learns.
What we call happiness is what we do not know.
Unhappiness does make people look stupid.
Men are not created to know, men are not created to understand ... and our illusions increase with our knowledge.