The most dangerous physicians are those born actors who imitate born physicians with a perfectly deceptive guile.

A man who possesses genius is insufferable unless he also possesses at least two other things: gratitude and cleanliness.

Mystical explanations are thought to be deep; the truth is that they are not even shallow.

Life is an instinct for growth, for survival, for the accumulation of forces, for power.

In every age the wisest have passed the identical judgment on life: it is worthless.

People who wish to numb our caution in dealing with them by means of flattery are employing a dangerous expedient, like a sleeping draught, which, if it does not put us to sleep, keeps us all the more awake.

Error has made man so deep, sensitive, and inventive that he has put forth such blossoms as religions and arts. Pure knowledge could not have been capable of it.