Let us look back a moment. The objectivity which Kant had allowed to exist Fichte has destroyed. There is _only_ the Ego. But the Ego presupposes a non-Ego, and therefore a kind of object. How the Ego comes to posit such an object, must the theoretical Theory of Science now proceed to show.
There are two extreme views respecting the relation of the Ego to the non-Ego, according as we start from the conception of cause, or that of substance. (1) Starting from the conception of cause, we have posited through the passiveness of the Ego an activity of the non-Ego. This passiveness of the Ego must have some ground. This cannot lie in the Ego, which in itself posits only activity. Consequently it lies in the non-Ego. Here the distinction between action and passion is apprehended, not simply as quantitative (_i. e._, viewing the passiveness as a diminished activity), but the passion is in quality opposed to the action; a presupposed activity of the non-Ego is, therefore, a real ground of the passiveness in the Ego. (2) Starting from the conception of substance, we have posited a passiveness of the Ego through its own activity. Here the passiveness in respect of quality is the same as activity, it being only a diminished activity. While, therefore, according to the first view, the passive Ego has a ground distinct in quality from the Ego, and thus a real ground, yet here its ground is only a diminished activity of the Ego, distinct only in quantity from the Ego, and is thus an ideal ground. The former view is dogmatic realism, the latter is dogmatic idealism. The latter affirms: all reality of the non-Ego is only a reality given it from the Ego; the former declares: nothing can be given, unless there be something to receive, unless an independent reality of the non-Ego, as thing in itself, be presupposed. Both views present thus a contradiction, which can only be removed by a new synthesis. Fichte attempted this synthesis of idealism and realism, by bringing out a mediating system of critical idealism. For this purpose he sought to show that the ideal ground and the real ground are one and the same. Neither is the simple activity of the Ego a ground for the reality of the non-Ego, nor is the simple activity of the non-Ego a ground for the passiveness in the Ego. Both must be conceived together in this way, viz., the activity of the Ego meets a _hindrance_, which is set up against it, not without some assistance of the Ego, and which circumscribes and reflects in itself this activity of the Ego. The hindrance is found when the subjective can be no farther extended, and the expanding activity of the Ego is driven back into itself, producing as its result self-limitation. What we call objects are nothing other than the different impinging of the activity of the Ego on some inconceivable hindrance, and these determinations of the Ego, we carry over to something external to ourselves, and represent them to ourselves as space filling matter. That which Fichte calls a hindrance through the non-Ego, is thus in fact the same as Kant calls thing essentially, the only difference being that with Fichte it is made subjective. From this point Fichte then deduces the subjective activities of the Ego, which mediate, or seek to mediate, theoretically, the Ego with the non-Ego—as imagination, representation (sensation, intuition, feeling), understanding, faculty of judgment, reason; and in connection with this he brought out the subjective projections of the intuition, space, and time.