Descartes - The Discourse on Method (1637)

I thought I must seek some other method...I believed I would have sufficient in the four following rules...

The first was never to accept anything as true that I did not know to be evidently so: that is to say, carefully to avoid precipitancy and prejudice, and to include in my judgements nothing more than what presented itself so clearly and distinctly to my mind that I might have no occasion to place it in doubt.

The second, to divide each of the difficulties that I was examining into as many parts as might be possible and necessary in order better to solve it.

The third, to conduct my thoughts in an orderly way, beginning with the simplest objects and the easiest to know, in order to climb gradually, as by degrees, as far as the knowledge of the most complex, and even supposing some order among those objects which do not precede each other naturally.

And the last, everywhere to make such complete enumerations and such general reviews that I would be sure to have omitted nothing.

***

But, as soon as I had acquired some general ideas about physics, and beginning to test them on various particular difficulties, I observed how far they can lead and how they differ from the principles which have been used up to now, I believed that I could not keep them hidden without sinning considerably against the law which obliges us to procure, by as much as is in us, the general good of all men. For they have made me see that it is possible to arrive at knowledge which is most useful in life, and that, instead of the speculative philosophy taught in the Schools, a practical philosophy can be found which, knowing the power and the effects of fire, water, air, the stars, the heavens and all the other bodies which surround us, as distinctly as we know the various trades of our craftsmen, we might put them in the same way to all the uses for which they are appropriate, and thereby make ourselves, as it were, the masters and possessors of nature.

***

I resolved to leave all these people to their disputes, and to speak only of what would happen in a new world, if God were now to create, somewhere in imaginary space, enough matter to compose it....