Variant: When it is not in our power to follow what is true, we ought to follow what is most probable.

I suppose therefore that all things I see are illusions; I believe that nothing has ever existed of everything my lying memory tells me. I think I have no senses. I believe that body, shape, extension, motion, location are functions. What is there then that can be taken as true? Perhaps only this one thing, that nothing at all is certain.

Wonder is the first of all the passions.

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

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 entire method consists in the order and arrangement of the things to which the mind's eye must turn so that we can discover some truth.

The two operations of our understanding, intuition and deduction, on which alone we have said we must rely in the acquisition of knowledge.