 Hume is Newtonian in much more than method. He sees that Newton is significantly different from John Locke (1632–1704) and the other Royal Society natural philosophers, because he rejects their mechanist picture of the world. Newton’s greatest discovery, the Law of Gravitation, is not a mechanical law. Hume explicitly models his account of the fundamental principles of the mind’s operations—the principles of association—on the idea of gravitational attraction. By appealing to these same principles throughout, Hume gives an explanation of these diverse phenomena that enable him to provide a unified and economical account of the mind.