The or "doctrine of science" was the great achievement of the German idealist philosopher J. G. Fichte. Daniel Breazeale presents accessible new translation of three works in which Fichte developed this philosophical system. The centerpiece of this volume is a new English translation of Fichte's only full-scale presentation of the principles of his philosophy, the (1794/95). Accompanying this are new translations of the work in which Fichte first publicly introduced his new system, (1794) and the (1795), which was intended as a companion to the Foundation. In addition Breazeale includes the transcripts of Fichte's unpublished "Zurich lectures" on his system (1794), translated here for the first time in English. Breazeale supplements his translations with an extensive historical and systematic introduction, detailed outlines of the contents and structure of the and , and copious scholarly annotation of the translated texts, helping to orient readers who may otherwise find themselves lost in the wilderness of Fichte's complex "derivations."