In his "Rules for the Direction of the Mind" (1628) and his "Discourse on Method" (1637) Descartes wrote about the scientific method that deals with scientific approach, thinking, a method which he had invented. He also wrote about shapes (Geometry), light (optics), and the weather (Meteorology). He then invented a way of describing shapes now called the Cartesian coordinate system, and a theory of what a rainbow is. Descartes' physics was important for a later famous thinker, Sir Isaac Newton, who said about him and so did James Hook: "If I have seen further it is because I was standing on the shoulders of giants!"