 A second aspect of Newton’s influence involves thinkers who attempted in one way or another to articulate, follow, or extend, the Newtonian “method” in natural philosophy when treating issues and questions that Newton ignored. Euclidean geometry and its methods were seen as a fundamental epistemic model for much of seventeenth-century philosophy—as is well known, Descartes’ Meditations attempts to achieve a type of certainty he likens to that found in geometry, and Spinoza wrote his Ethics according to the “geometrical method”. Propositions deduced from axioms in Euclidean geometry were seen as paradigm cases of knowledge. We might see Newton’s work as providing eighteenth-century philosophy with one of its primary models, and with a series of epistemic exemplars as well. But part of philosophy’s task was to articulate precisely what the new Newtonian method involved. David Hume is perhaps clearest about this aspect of Newton’s influence: his Treatise of 1739 has the subtitle, “An Attempt to Introduce the Experimental Method of Reasoning Into Moral Subjects”, and there can be little doubt that he meant (at least in part) the method of the Opticks and the Principia (DePierris 2012). Indeed, as Hume’s text makes abundantly clear, various eighteenth-century philosophers, including not only Hume in Scotland but Jean-Jacques Rousseau on the Continent, were taken to be, or attempted to become, “the Newton of the  mind”.[5]  For Hume, this meant following what he took to be Newton’s empirical method by providing the proper description of the relevant phenomena and then finding the most general principles that account for them. Of course, one aspect of Hume’s work is to provide an analysis of the concept of causation that is far more extensive than anything found in Newton, which has a substantial impact on what counts as an “account” of a phenomenon. This method would allow us to achieve the highest level of knowledge attainable in the realm of what Hume calls “matters of  fact”.[6]