Science only means knowledge; and for [Greek] ancients it did only mean knowledge. Thus the favorite science of the Greeks was Astronomy, because it was as abstract as Algebra. ... We may say that the great Greek ideal was to have no use for useful things. The Slave was he who learned useful things; the Freeman was he who learned useless things. This still remains the ideal of many noble men of science, in the sense they do desire truth as the great Greeks desired it; and their attitude is an external protest against vulgarity of utilitarianism.

You cannot grow a beard in a moment of passion.

The chief object of education is not to learn things but to unlearn things.

A man was meant to be doubtful about himself, but undoubting about the truth; this has been exactly reversed.

A man does not know what he is saying until he knows what he is not saying.

We are to regard existence as a raid or great adventure; it is to be judged, therefore, not by what calamities it encounters, but by what flag it follows and what high town it assaults. The most dangerous thing in the world is to be alive; one is always in danger of one's life. But anyone who shrinks from that is a traitor to the great scheme and experiment of being.

But a somewhat more liberal and sympathetic examination of mankind will convince us that the cross is even older than the gibbet, that voluntary suffering was before and independent of compulsory; and in short that in most important matters a man has always been free to ruin himself if he chose.