Divide each difficulty into as many parts as is feasible and necessary to resolve it.

Even the mind depends so much on temperament and the disposition of one's bodily organs that, if it is possible to find a way to make people generally more wise and more skilful than they have been in the past, I believe that we should look for it in medicine. It is true that medicine as it is currently practiced contains little of much use.

The first precept was never to accept a thing as true until I knew it as such without a single doubt.

I hope that posterity will judge me kindly, not only as to the things which I have explained, but also to those which I have intentionally omitted so as to leave to others the pleasure of discovery.

Although my knowledge grows more and more, nevertheless I do not for that reason believe that it can ever be actually infinite, since it can never reach a point so high that it will be unable to attain any greater increase.

In order to improve the mind, we ought less to learn, than to contemplate.

How can you be certain that your whole life is not a dream?