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Descartes, René. 1596-1650. French mathematician and philosopher.

"Cogito, ergo sum." (I think, therefore I am.)

"Thus what I thought I had seen with my eyes, I actually grasped solely with the faculty of judgment, which is in my mind."

"Each problem that I solved became a rule which served afterwards to solve other problems"

"I thought the following four rules would be enough, provided that I made a firm and constant resolution not to fail even once in the observance of them.
The first was never to accept anything as true if I had not evident knowledge of its being so; that is, carefully to avoid precipitancy and prejudice, and to embrace in my judgment only what presented itself to my mind so clearly and distinctly that I had no occasion to doubt it.
The second, to divide each problem I examined into as many parts as was feasible, and as was requisite for its better solution.
The third, to direct my thoughts in an orderly way; beginning with the simplest objects, those most apt to be known, and ascending little by little, in steps as it were, to the knowledge of the most complex; and establishing an order in thought even when the objects had no natural priority one to another.
And the last, to make throughout such complete enumerations and such general surveys that I might be sure of leaving nothing out."

"It is not enough to have a good mind. The main thing is to use it well."

"These long chains of perfectly simple and easy reasoning by means of which geometers are accustomed to carry out their most difficult demonstrations had led me to fancy that everything that can fall under human knowledge forms a similar sequence; and that so long as we avoid accepting as true what is not so, and always preserve the right order of deduction of one thing from another, there can be nothing too remote to be reached in the end, or to well hidden to be discovered."
Discours de la Méthode. 1637.

"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."
La Geometrie.


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 Rene Descartes Video




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