One must be oneself very little of a philosopher not to feel that the finest privilege of our reason consists in not believing in anything by the impulsion of a blind and mechanical instinct, and that it is to dishonour reason to put it in bonds as the Chaldeans did. Man is born to think for himself.

There comes a moment during which almost every girl or boy falls into melancholy; they are tormented by a vague inquietude which rests on everything and finds nothing to calm it. They seek solitude; they weep; the silence to be found in cloister attracts them: the image of peace that seems to reign in religious houses seduces them. They mistake the first manifestations of a developing sexual nature for the voice of God calling them to Himself; and it is precisely when nature is inciting them that they embrace a fashion of life contrary to nature's wish.

The Christian religion teaches us to imitate a God that is cruel, insidious, jealous, and implacable in his wrath.

All things must be examined, debated, investigated without exception and without regard for anyone's feelings.

You risk just as much in being credulous as in being suspicious.

Instinct guides the animal better than the man. In the animal it is pure, in man it is led astray by his reason and intelligence.

Time, matter, space - all, it may be, are no more than a point.