How old the world is! I walk between two eternities.... What is my fleeting existence in comparison with that decaying rock, that valley digging its channel ever deeper, that forest that is tottering and those great masses above my head about to fall? I see the marble of tombs crumbling into dust; and yet I don't want to die!

As long as the centuries continue to unfold, the number of books will grow continually, and one can predict that a time will come when it will be almost as difficult to learn anything from books as from the direct study of the whole universe. It will be almost as convenient to search for some bit of truth concealed in nature as it will be to find it hidden away in an immense multitude of bound volumes.

My ideas are my whores.

There is only one virtue, justice; only one duty, to be happy; only one corollary, not to overvalue life and not to fear death.

Scepticism is the first step toward truth.

Integrity is the evidence of all civil virtues.

Shakespeare's fault is not the greatest into which a poet may fall. It merely indicates a deficiency of taste.