Descartes

If this discourse seems too long to be read at a sitting you may divide it into six parts. In 1 you will find various considerations regarding the sciences; in 2 the main rules of the method that the author has sought; in 3 some of the moral rules he has derived from this method; in 4 the arguments by which he proves the existence of God and the human soul, on which his metaphysics is based; in 5 the order of the questions in physics that he has investigated, particularly the explanation of the movement of the heart and of some other problems in the medical sphere, and also the difference between our soul and that of the lower animals; and in 6 the things he believes are needed if we are to go further than he has in the investigation of nature, and his reasons for writing this discourse.

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•Good sense is the best shared-out thing in the world; for everyone thinks he has such a good supply of it that he doesn’t want more, even if he is extremely hard to please about other things. Since it’s not likely that everyone is mistaken about this, it is evidence that

the •power of judging well and of telling the true from the false—which is what we properly call •‘good sense’ or •‘reason’—is naturally equal in all men;

thus it is also evidence that

our opinions differ not because some of us are more reasonable than others, but solely because we take our thoughts along different paths and don’t attend to the same things.

For it isn’t enough to have a good mind; what matters most is using it well. ·Sheer quality of intellect doesn’t make the difference between good and bad·: the greatest souls are capable of the greatest vices as well as the greatest virtues. ·Nor is nimbleness of intellect the key to making discoveries·: those who go very slowly but always on the right path can make much greater progress than those who sprint and go astray.

As for me, I have never presumed my mind to be in any way better than the minds of people in general. Indeed, I have often ·had a...