 Descartes’ plan is to reduce the class of metaphysically suspect properties, such as heat, weight, taste, to the empirically quantifiable attributes of size, shape, and motion. In other words, Descartes intends to replace the “mentally” influenced depiction of physical qualities in Scholastic natural philosophy with a theory that requires only the properties of extension to describe the manifest order of the natural world. Consequently, Descartes was an early exponent of what came to be known as the “primary/secondary” property distinction, a concept that was very much “in the air” among the critics of Scholasticism.