The purpose of this chapter is to trace the development that Fichte's philosophical project undergoes during the period from 1793 to 1799. Our ultimate goal will be to understand how his conception of that project as a theory of subjectivity emerges out of earlier attempts to uphold the thesis of the unity of theoretical and practical reason. As we shall see, in his early philosophical writings Fichte concentrates primarily on the task of demonstrating the unity of reason in the second of the three senses outlined in Chapter 1 (where both theoretical and practical reason are to be brought together into one system that proceeds from a single first principle). By 1797, however, Fichte comes to have a different understanding of his enterprise, one that embodies the third sense of the unity of reason, according to which theoretical and practical reason are to be comprehended as a single faculty, each of which exhibits the same “structure” of reason in general. The story of this transformation is significantly complicated by the fact that for Fichte the issue of the unity of reason is inextricably bound up with his wish to find a positive proof of the reality of practical reason. Initially, it is the latter concern that dominates his attempts to construct a new philosophical system.