

PROPERTY OF A WEST COAST COLLECTOR
The now famous Cartesian method is outlined in the Four Rules presented in Book II. Books III and IV contain discussions of metaphysics and physiology, the latter of which includes a reference to Harvey’s discovery of the circulation of blood. The appended essays on optics, meteorology, and geometry demonstrate the type of results that can be obtained by employing his rules of scientific investigation. His essay on optics contains important observations and experiments on refraction as well as one of the earliest mentions of Snell’s law of refraction. His brilliant treatise on geometry laid the foundation for analytic geometry.