 In the Schematism, Kant undertakes to identify the particular mechanism that enables the pure concepts of the understanding to subsume sensible intuitions, with which they are heterogeneous. The categories must be “schematized” because their non-empirical origin in pure understanding prevents their having the sort of sensible content that would connect them immediately to the objects of experience; transcendental schemata are mediating representations that are meant to establish the connection between pure concepts and appearances in a rule-governed way. Mathematical concepts are discussed in this context since they are unique in being pure but also sensible concepts: they are pure because they are strictly a priori in origin, and yet they are sensible since they are constructed in concreto. (Kant further complicates this issue by identifying number as the pure schema of the category of magnitude (Longuenesse 1998).) There arises an interpretive question as to whether mathematical concepts, whose conceptual content is given sensibly, require schematization by a distinguishable “third thing”, and, if so, what it amounts to (Leavitt 1991; Young 1984). More broadly, the question arises as to how the transcendental imagination, the faculty responsible for schematism, operates in mathematical contexts (Domski 2010).