Published 1637 as an annex to Discours de la méthode ("Discourse on the Method of Rightly Conducting the Reason, and Seeking Truth in the Sciences").
All problems of geometry can easily be reduced to such conditions, so to construct them one only has to know the length of certain straight lines.
Note on the right border: How the Arithmetic calculus relates to the operations of Geometry. |
And just as all arithmetic consists but of four or five operations, which are Addition, Subtraction, Multiplication, Division and Taking Roots, which can be regarded as a special case of Division: So in geometry the only thing one has to do with regard to the lines one is searching, in order to prepare them to become known, is to adjust others to them or make them visible. Once you have one, which I shall call unity so that we can put them into relation with numbers all the better, & which can normally be taken at your discretion; furthermore when you also have two others, you find a fourth one, which relates to one of the two like the other to unity, this then is the same as Multiplication; likewise, by finding a fourth one that relates to one of the two like unity to ...