We have now reached the third part of the Theory of Science, via., _the foundation of the practical_. We have seen that the Ego represents. But that it may represent does not depend upon the Ego alone, but is determined by something external to it. We could in no way conceive of a representation, except through the presupposition that the Ego finds some hindrance to its undetermined and unlimited activity. Accordingly the Ego, as intelligence, is universally dependent upon an indefinite, and hitherto wholly indefinable non-Ego, and only through and by means of such non-Ego, is it intelligence. A finite being is only finite as intelligence. These limits, however, we shall break through. The practical law which unites the finite Ego with the infinite, can depend upon nothing external to ourselves. The Ego, according to all its determinations, should be posited absolutely through itself, and hence should be wholly independent of every possible non-Ego. Consequently, the absolute Ego and the intelligent Ego, both of which should constitute but one, are opposed to each other. This contradiction is obviated, when we see that because the absolute Ego is capable of no passiveness, but is absolute activity, therefore the Ego determines, through itself, that hitherto unknown non-Ego, to which the hindrance has been ascribed. The limits which the Ego, as theoretic, has set over against itself in the non-Ego, it must, as practical, seek to destroy, and absorb again the non-Ego in itself (or conceive it as the self-limitation of the Ego). The Kantian primacy of the practical reason is here made a truth. The transition of the theoretical part into the practical, the necessity of advancing from the one to the other, Fichte represents more closely thus:—The theoretical Theory of Science had to do with the mediation of the Ego, and the non-Ego. For this end it introduced one connecting link after another, without ever attaining its end. Then enters the reason with the absolute and decisive word: “there ought to be no non-Ego, since the non-Ego can in no way be united with the Ego;” and with this the knot is cut, though not untied. Thus it is the incongruity between the absolute (practical) Ego, and the finite (intelligent) Ego, which is carried over beyond the theoretical province into the practical. True, this incongruity does not wholly disappear, even in the practical province, where the act is only an infinite striving to surpass the limits of the non-Ego. The Ego, so far as it is practical, has, indeed, the tendency to pass beyond the actual world, and establish an ideal world, as it would be were every reality posited by the absolute Ego; but this striving is always confined to the finite partly through itself, because it goes out towards objects, and objects are finite, and partly through the resistance of the sensible world. We ought to seek to reach the infinite, but we cannot do it; this striving and inability is the impress of our destiny for eternity.