 In contrast to Fichte’s rather cursory treatment of purely theoretical philosophy, ethics or “practical philosophy,” which analyzes the determinate ways in which willing and acting are determinable by principles of pure reason, constitutes a major portion of the Jena system, and the System of Ethics is Fichte’s longest single book. Whereas theoretical philosophy explains how the world necessarily is, practical philosophy explains how the world ought to be, which is to say, how it ought to be altered by rational beings. Ethics thus considers the object of consciousness not as something given or even as something constructed by necessary laws of consciousness, but rather as something to be produced by a freely acting subject, consciously striving to establish and to accomplish its own goals and guided only by its own self-legislated laws. The specific task of Fichte’s ethics is therefore, first of all, to deduce the categorical imperative (in its distinctively moral sense) from the general obligation to determine oneself freely, and, second, to deduce from this the particular obligations that apply to every free and finite rational being.