Life without sex might be safer but it would be unbearably dull. It is the sex instinct which makes women seem beautiful, which they are once in a blue moon, and men seem wise and brave, which they never are at all. Throttle it, denaturalize it, take it away, and human existence would be reduced to the prosaic, laborious, boresome, imbecile level of life in an anthill.

Moral certainty is always a sign of cultural inferiority. The more uncivilized the man, the surer he is that he knows precisely what is right and what is wrong.

It is difficult to imagine anyone having any real hopes for the human race in the face of the fact that the great majority of men still believe that the universe is run by a gaseous vertebrate of astronomical heft and girth, who is nevertheless interested in the minutest details of the private conduct of even the meanest man.

The most disgusting cad in the world is the man who on the grounds of decorum and morality avoids the game of love. He is one who puts his own ease and security above the most laudable of philanthropies.

One seldom discovers a true believer that is worth knowing.

There is no record in human history of a happy philosopher: they exist only in romantic legend.

The true aim of medicine is not to make men virtuous; it is to safeguard and rescue them from the consequences of their vices. The physician does not preach repentance; he offers absolution.