 Cohen retired from Marburg in 1912, in order to teach at the Academy of Jewish Sciences, a rabbinical seminary in Berlin, where he remained until his death. In 1908 he had written his Ethics of Maimonides, and after 1912 he worked above all else on religious philosophy, writing The Concept of Religion in the System of Philosophy (1915) and his monumental Religion of Reason Out of the Sources of Judaism, which appeared in 1919, after his death. The Religion’s significance is difficult to overstate: it has been called “the single most consequential work of Judaic thought in the period of the nineteenth and twentieth centuries” (Dietrich 2000). In it, Cohen articulates a conception of a “religion of reason,” and argues that fundamental concepts of Judaism, as they are revealed in historical Jewish texts, were the original sources of that religion of reason.