 However, Cohen would not remain satisfied with his account of calculus’ foundational concepts and their significance for a philosophical theory of knowledge. His final major work in epistemology was the 1902 Logic of Pure Knowledge, the first part of his projected System of Philosophy. In that book, Cohen claims that there is an important connection between the concepts of infinitesimals and infinities, and something he now calls “pure thinking.” For Cohen, thinking is pure just in case it is independent of any and all influences that are external to thought or reason. Nothing is given to pure thinking – not the data of sensible intuition, not the activity of a Fichtean I, not the Absolute. Cohen claims that the infinitesimal calculus is the paradigmatic example of “the triumph of pure thinking” (Cohen 1902, 35). But more than that, he thinks an analysis of the infinite is precisely what first raises the philosophical question of pure thinking – that is, the question of how pure thinking functions to let mathematical natural science represent objects (Cohen 1902, 35).