This dissertation explores the problem of how knowledge is possible, given that knowledge is necessarily rooted in the reality of the knower. The Kantian critical philosophy defeats Humean skepticism by demonstrating the a priori necessity of certain categorical functions at the root of all human cognition, but ultimately results in merely shifting the problem of certainty to these same functions. Ernst Cassirer’s Philosophy of Symbolic Forms seeks to extend the critical philosophy of Kant beyond the limits of theoretical thinking, and thereby broadens the functional foundations of cognition to include all symbolic modes of thinking in a unified system of human cognition. However, this expansion of the system of knowledge only serves to further highlight the fundamental problem of how knowledge of any sort can be a “symbol” of reality, when the symbolic form that produces that symbol always involves the mediation of reality in some way. This general problem is described throughout Cassirer’s writings in terms of a dialectic of spirit (Geist) and life (Leben), which, he argues, is the fundamental dialectic to which all other oppositions in the history of metaphysics can ultimately be reduced. In the present work, the nature of this dialectic is described and tied to the general problem of knowledge within any systematic critical philosophy, as seen in Cassirer’s philosophy as well as the works of Peirce, Kierkegaard, Nietzsche, and Wittgenstein. Through this discussion, Cassirer’s own esoteric conception of a monadic metaphysics will be revealed, and the key importance of freedom as a solution to this dialectic will be drawn from his interpretation of earlier philosophers, particularly Nicolaus Cusanus. / Philosophy