 Cohen’s period of philosophical productivity spanned the duration of the German empire, from the late 1860s until 1918. We can distinguish three periods in his writing (van der Linden 1988, 205–6; Bonaunet 2004: 22ff). The first, early period is characterized by Cohen’s attempts to develop his own views as commentaries on Kant. During this period, he wrote Kant’s Theory of Experience, Kant’s Foundations of Ethics, and Kant’s Foundations of Aesthetics. The second period marks Cohen’s mature philosophical work, which took the form of his multi-volume System of Philosophy. In the System, Cohen explicitly abandoned central Kantian doctrines, and presented his views systematically, and as his own, rather than offering them as interpretations of Kant. The System included The Logic of Pure Knowledge, The Ethics of Pure Will, and The Aesthetics of Pure Feeling. (He planned, but never wrote, a fourth part of the System on the psychology of “cultural consciousness.” This fourth part was to provide the systematic foundation for the other three parts of the System [see Adelmann 1968 and Moynahan 2018].) Finally, although Cohen had been interested in religious questions throughout his career, in the last years of his life they were his overwhelming concern. It was during this period that he wrote his Religion of Reason Out of the Sources of Judaism.