 The first aspect of Newton’s argument is to indicate that mechanical explanations are predicated on referencing certain kinds of qualities when investigating natural phenomena, and that these qualities themselves are therefore not subject to mechanical explanation. For instance, since mechanist explanations—say, of the way in which magnets attract iron filings across a table—must refer to qualities such as the extension of the bodies subject to the explanations, then we cannot give a mechanist explanation of extension itself. Of course, Leibniz might reply that we need not provide any explanation of the basic qualities of bodies that figure in mechanical explanations, for those properties have been chosen by the “moderns” precisely because they are perfectly intelligible on their own, perhaps unlike various qualities attributed to “Scholastic” accounts of natural phenomena. The second aspect of Newton’s argument is more intriguing—it also harkens back to Locke’s discussion with Stillingfleet, for Locke had contended that God may have superadded not only gravity to material bodies, but also the power of thought, linking them because he believed that neither could be rendered intelligible using any philosophical means at his disposal. That is, from Locke’s point of view, we know that human beings—which are, or at least contain, material bodies with size, shape, motion and solidity, along with parts characterized by those qualities—are capable of thought, but since we cannot discern how any material thing could possibly have that capacity, we conclude that God may have superadded that feature to us, or to our bodies. Thought and gravity are dis-analogous in the sense that we did not require anything like Newton’s theory to convince us that human beings can think, but they are otherwise analogous. Newton then attempts to make the following argument: since Leibniz would have to agree that thinking is not a mechanical process, and not mechanically explicable, he must agree that there is at least one aspect of the world that has the following two features, (1) it is not mechanical; and, (2) it is clearly not to be rejected on that ground alone. He attempts to liken gravity (as he understands it) to thinking (as he believes Leibniz is required to understand it), arguing that despite the fact that it is not mechanical—it cannot be explained mechanically—it should not be rejected on that ground. This argument may be predicated on the view that human beings, material things, or at least partially material things, do the thinking, rather than immaterial things, such as minds or souls, for if one attributes all thought to an immaterial mind or soul, then there is no pressure to say that anything in nature, or perhaps even any aspect of anything in nature, has a feature that cannot be mechanically explicated. If one accepts Locke’s view (apparently also endorsed by Newton) that we should attribute thinking to material things, or to aspects of material things, then perhaps Newton has successfully followed Locke in likening gravity to thought, thereby making room for aspects of nature that are not mechanical after all. This vexing issue would continue to generate debates amongst Newton’s and Leibniz’s various followers in England, and on the Continent, respectively.