The human body is a machine that winds up its own springs: it is a living image of the perpetual motion.

It is convention and arbitrary rewards which make all the merit and demerit of what we call vice and virtue.

Man is a machine and in the whole universe there is but a single substance, matter, variously modified.

Therefore, since we may say, after such long experience, that religion does not imply exact honesty, we are authorized by the same reasons to think that atheism does not exclude it.

Nothing is absolutely unjust. There is no real equity, no total grandeur, no pure vice, no absolute crime.

The human body is a machine that winds up its own springs: it is a living image of the perpetual motion.

The brain has muscles for thinking as the legs have muscles for walking.