It is always by way of pain one arrives at pleasure.

Any punishment that does not correct, that can merely rouse rebellion in whoever has to endure it, is a piece of gratuitous infamy which makes those who impose it more guilty in the eyes of humanity, good sense and reason, nay a hundred times more guilty than the victim on whom the punishment is inflicted.

If Nature denies eternity to beings, it follows that their destruction is one of her laws. Now, once we observe that destruction is so useful to her that she absolutely cannot dispense with it from this moment onward the idea of annihilation which we attach to death ceases to be real what we call the end of the living animal is no longer a true finish, but a simple transformation, a transmutation of matter. According to these irrefutable principles, death is hence no more than a change of form, an imperceptible passage from one existence into another.

Between understanding and faith immediate connections must subsist.

Crime is to the passions what nervous fluid is to life: it sustains them, it supplies their strength.

One is never so dangerous when one has no shame, than when one has grown too old to blush.

In order to know virtue, we must first acquaint ourselves with vice.