If we were magically shrunk and put into someone's brain while she was thinking, we would see all the pumps, pistons, gears and levers working away and we would be able to describe the workings completely, in mechanical terms, thereby completely describing the thought processes of the brain. But that description would not contain any mention of thought! It would contain nothing but descriptions of pumps, pistons, levers!

The greatness of a life can only be estimated by the multitude of its actions. We should not count the years, it is our actions which constitute our life.

Nothing is accomplished all at once, and it is one of my great maxims, and one of the most completely verified, that Nature makes no leaps: a maxim which I have called the law of continuity.

To love is to place happiness in the heart of another.

The knowledge which we have acquired ought not to resemble a great shop without order, and without an inventory; we ought to know what we possess, and be able to make it serve us in need.

There is no way in which a simple substance could begin in the course of nature, since it cannot be formed by means of compounding.

...a distinction must be made between true and false ideas, and that too much rein must not be given to a man's imagination under pretext of its being a clear and distinct intellection.