Most commentators on Spengler's philosophy tend to focus on the details of his cyclical theory of world-history, according to which history should be understood in terms of the rise and fall of great cultures. I argue that Spengler's philosophy of history is itself an expression of his primary concern with philosophical analysis of the structures of human consciousness, and that an awareness of Spengler's account of the existential structures of subjective consciousness enables one to grasp the reasoning behind some of (...) the key features of his philosophy of history, such as his cultural isolation hypothesis and critique of Eurocentric historiography. I further argue that the way to access Spengler's theory of consciousness, and the ways in which it informs his philosophy of history, is via his critical engagement with the Kant character that recurs in the first volume of The Decline of the West. (shrink)