|We have yet another French mathematician from the 1600s to thank for our system of plotting coordinates on a graph. (Can you believe how many good mathematicians there were in France back then?) René Descartes (1596–1650) published his treatise, La géométrie, in 1637, as an appendix to his scientific and philosophical masterpiece, Discours de la methodé ("Discourse on the Method"). La géométrie was the only mathematical work Descartes ever published, but it changed mathematics forever by inventing a way of linking algebra and geometry. Today, when we use coordinates to define the points in a plane, we're using the Cartesian Coordinate System, named after Descartes.