 When Newton wrote the Principia between 1684 and 1686, he was not contributing to a preexisting field of study called mathematical physics; he was attempting to show how philosophers could employ various mathematical and experimental methods in order to reach conclusions about nature, especially about the motions of material bodies (Janiak 2015, Chapter One). In his lectures presented as the Lucasian Professor at Cambridge, Newton had been arguing since at least 1670 that natural philosophers ought to employ geometrical methods in order to understand various phenomena in  nature.[18]  The Principia represented his attempt to reorient natural philosophy, taking it in a direction that neither his Aristotelian predecessors, nor his Cartesian contemporaries, had envisioned. He did not immediately convince many of them of the benefits of his approach. Just as his first publication in optics in 1672 sparked an intense debate about the proper methods for investigating the nature of light—and much else besides—his Principia sparked an even longer lasting discussion about the methodology that philosophers should adopt when studying the natural world. This discussion began immediately with the publication of the Principia, despite the fact that its first edition contained few explicit methodological remarks (Smith 2002: 138–39). It intensified considerably with the publication of its second edition in 1713, which contained many more remarks about methodology, including many attempts at defending the Newtonian method. Indeed, many of Newton’s alterations in that edition changed the presentation of his methods. Discussions of methodology would eventually involve nearly all of the leading philosophers in England and on the Continent during Newton’s lifetime.