We must know where to doubt, where to feel certain, where to submit. He who does not do so, understands not the force of reason.

The heart has its order, the mind has its own, which uses principles and demonstrations. The heart has a different one. We do not prove that we ought to be loved by setting out in order the causes of love; that would be absurd.

Il n'est pas certain que tout soit incertain. (Translation: It is not certain that everything is uncertain.)

Our senses will not admit anything extreme. Too much noise confuses us, too much light dazzles us, too great distance or nearness prevents vision, too great prolixity or brevity weakens an argument, too much pleasure gives pain, too much accordance annoys.

Let us, then, take our compass; we are something, and we are not everything. The nature of our existence hides from us the knowledge of first beginnings which are born of the nothing; and the littleness of our being conceals from us the sight of the infinite. Our intellect holds the same position in the world of thought as our body occupies in the expanse of nature.

Do you wish people to speak well of you? Then do not speak at all yourself.

Concupiscence and force are the source of all our actions; concupiscence causes voluntary actions, force involuntary ones.