 Although the endeavors of Locke and Newton are often considered complementary, there are questions about how Locke responded to the Principia, both in terms of its methodology and its epistemological implications.  With regard to the former, how far did Locke go in absorbing or incorporating the methodology that Newton had forged?  As a number of commentators have emphasized, the new science was itself in flux at this time, with natural history being gradually sidelined by Newton’s approach, an experimentalism that was theoretical and mathematical (see, e.g., Anstey 2011; Roux, 2013). Given that Locke had had Boyle as his mentor, but was greatly impressed by Newton’s Principia, it is natural to ask whether a similar shift was occurring in Locke’s own thought. Although Locke was clearly influenced by Newton, his allegiances to certain older ideas ran deep. Graciela De Pierris (2006) explains Locke’s failure to adopt the method of inductive proof in terms of his devotion to the ideal of demonstrative knowledge, as combined with a belief in hidden primary qualities. 