  In establishing the ground for science, Descartes was at the same time overthrowing a system of natural philosophy that had been established for centuries—a qualitative, Aristotelian physics. In a letter to Mersenne, dated 28 January 1641, Descartes says “these six meditations contain all the foundations of my physics. But please do not tell people, for that might make it harder for supporters of Aristotle to approve them. I hope that readers will gradually get used to my principles, and recognize their truth, before they notice that they destroy the principles of Aristotle.” Unlike his earlier work, The World, the Meditations parts ways with the “old” science without explicitly forwarding controversial views, like that of the Copernican heliocentric model of the solar system. Specifically, the Cartesian view denies that physics is grounded in hot, cold, wet, and dry. It argues that contrary to Aristotle’s view, such “qualities” are not properties of bodies at all. Rather, the only properties of bodies with which the physicist can concern him or herself are size, shape, motion, position, and so on—those modifications that conceptually (or logically) entail extension in length, breadth, and depth. In contrast to Aristotle’s “qualities,” the properties (or modes) of bodies dealt with in Cartesian physics are measurable specifically on ratio scales (as opposed to intensive scales), and hence are subject in all the right ways to mathematics (Buroker, pp.  596–7). This conception of matter, conjoined with the sort of mathematics found in the Geometry, allies itself with the work of such Italian natural philosophers as Tartaglia, Ubaldo, and Galileo, and helps further the movement of early thinkers in their attempts to establish a mathematical physics.