 Boyle’s best known work in natural philosophy is The Origin of Forms and Qualities According to the Corpuscular Philosophy (1666) (hereafter “OFQ”). A large part of OFQ is devoted to reports of experiments intended to show the superiority of CT over its scholastic and chemical competitors (OFQ [1991: 18]; also Boyle 1674). According to the theoretical part, matter is one extended impenetrable substance to which motion in accord with contingent laws is added by God. Local motion, the “grand agent” of natural change (OFQ [1991: 19]), divides matter into parts, each modified by a determinate size, shape, and local motion. The corresponding determinable modifications are inseparable from every part of matter, and designated “primary” because they are simple, primitive, and sufficient to derive all qualities (OFQ [1991: 97]). Texture, a fourth primary modification, is the configuration, i.e., mutual orientation and order, of the corpuscular parts of a body (OFQ [1991: 30]). Texture is composed of the primary affections of many insensible particles which jointly form a novel modification that none of the particles has by itself, much as TINs do for Descartes. All four primary affections are intrinsic properties. Boyle calls them “mechanical affections” (hereafter “MAs”) because, he says, the operations of machines are commonly explained by them (OFQ [1991: 18–21]). The stated aim of OFQ is