 Many of Newton’s readers in 1713 would have granted him the following inference: although we do not have any perceptions of, say, the interior of the earth, or even of many ordinary objects within our grasp, we can reasonably infer that everything with certain basic properties—something akin to what John Locke, borrowing a term of Robert Boyle’s, called the “primary qualities”—at the macroscopic level is comprised of micro-particles that are characterized by those same basic properties. But at the end of his gloss of Rule 3, Newton applies this same (or analogous) reasoning to the force of gravity, arguing as follows: since we experience the fact that all bodies on or near the earth gravitate toward the earth—in cases such as free fall—and that the moon gravitates toward the earth, etc., we can infer that all bodies everywhere gravitate toward all other bodies. This argument would appear to suggest that gravity—which, as we have seen, is a kind of impressed force, an action—is somehow akin to qualities like extension and impenetrability. So is Newton suggesting that gravity is actually a quality of all bodies? He did not explicitly endorse that claim, but Cotes did in a famous passage in his editor’s preface (Newton 1999, 391-92). Many understood Cotes to be speaking for Newton, just as they interpreted Clarke a few years later. Leibniz and his followers pounced: if Newton regards gravity as a quality, as a power of attraction, then he had indeed revived the occult qualities of the Scholastics, for here we have a quality that is not explicable in mechanical terms. Unlike the usual properties of extension, impenetrability and mobility discussed by Cotes, gravity seemed like a hidden power. This topic became the subject of intense debate throughout the first half of the eighteenth century (see the last section below).