 Ernst Cassirer occupies a unique place in twentieth-century philosophy. His work pays equal attention to foundational and epistemological issues in the philosophy of mathematics and natural science and to aesthetics, the philosophy of history, and other issues in the “cultural sciences” broadly conceived. More than any other German philosopher since Kant, Cassirer thus aims to devote equal philosophical attention both to the (mathematical and) natural sciences (Naturwissenschaften) and to the more humanistic disciplines (Geisteswissenschaften). In this way, Cassirer, more than any other twentieth-century philosopher, plays a fundamental mediating role between C. P. Snow’s famous “two cultures.” He also plays a similarly mediating role between the two major traditions in twentieth-century academic philosophy – the “analytic” and “continental” traditions – whose radically different (and often mutually uncomprehending) perspectives on the relationship between scientific and humanistic elements in their subject gave rise to a fundamental split or gulf between philosophy as it came to be practiced in the Anglo-American world, on the one side, and as it was practiced in most of the rest of the world, on the other. Cassirer, by contrast, had fruitful philosophical relations with leading members of both traditions – with Moritz Schlick, the founder and guiding spirit of the Vienna Circle of logical empiricists, whose work in logic and the philosophy of science had a decisive influence on the development of philosophy in the United States, and with Martin Heidegger, the creator of a radical “existential-hermeneutical” version of Husserlian phenomenology which quickly became dominant in continental Europe.