This remarkable volume provides a critical assessment of the Neoclassical Synthesis , long regarded as the standard interpretation of Keynes. Taking issue with this orthodoxy, the author offers a unique interpretation of the foundation of modern macroeconomics, arguing that the subject derives from the conflict between two research programmes inspired by different paradigms in physics: the Newtonian programme of Hicks and the Einsteinian approach of Keynes. Part I compares Hick's Newtonian programme with the Einsteinian programme underlying the General Theory , and argues that only the latter challenges atomism and accounts for time in an essential way. Part II reconstructs the development of the Neoclassical Synthesis and underlines that some of its key products represent pragmatic deviations from Hick's 'pure' Newtonian programme. Part III examines microfoundations approaches that seek to remedy the flaws of the Neoclassical Synthesis and concludes that they are fatally undermined by their inability to grasp the Einsteinian foundations of Keynes's approach. Original and provocative in its reflections, Keynes and the Neoclassical Synthesis not only offers a fresh interpretation of Keynes but makes an important contribution to debates within post-Keynesian economics. It will thus be of interest to all those interested in Keynes's place in the history of economic thought and macroeconomic methodology.