Fichte's 1804 Wissenschaftslehre, or The Science of Knowing, consists of a series of lectures he delivered in his Berlin home to members of the city's political and cultural elite in 1804. The lectures mark a dramatic shift in the terminology and methodology he uses to explore the nature of knowledge and reality as presented in his philosophical system, the Wissenschaftslehre. Although not published during his lifetime, Fichte's 1804 lectures provide a systematic update to his philosophy of knowledge and being, which was only hinted at in print in popular presentations like Characteristics of the Present Age (1805) and The Way Towards the Blessed Life (1806). In fact, these lectures contain Fichte's first public articulation of his philosophical position in the wake of the professional disaster of the "atheism controversy." This volume of new essays not only offers readers novel interpretations of the lectures but also introduces and clarifies key concepts, debates the relationship of the lectures to Fichte's Jena presentation of the Wissenschaftslehre, and examines issues related to his method and system of idealism.