In this thesis, I provide a reading of the Transcendental Analytic of Kants Critique of Pure Reason which is very sympathetic to Beatrice Longuenesses interpretation as put forth in her commentary Kant and the Capacity to Judge. I criticize her work, however, as implementing an improper retroactivity which can be corrected by understanding Kants architectonic of mind not as a preformed entity, but a product which will develop into an organism. Epigenesis provides the model for this development which culminates in Reason, existing first as Sensibility and then Understanding. This thesis is to function as a prolegomena, since here Sensibility and Understanding, their interaction and the grounds for their similarity, are the topic. I attempt to demonstrate how it is that Kants Function is concept which connects Sensibility and Understanding to one another, and that it provides a means to account for their similarities.