Here we have concluded the first division of Greek philosophy, and we have now to pass to the second period. The first period of Greek philosophy extended to Aristotle, to the attainment of a scientific form in which knowledge has reached the standing of free thought. Thus in Plato and Aristotle the result was the Idea; yet we saw in Plato the universal made the principle in a somewhat abstract way as the unmoved Idea; in Aristotle, on the other hand, thought in activity became absolutely concrete as the thought which thinks itself. The next essential, one which now is immediately before us, must be contained in that into which Philosophy under Plato and Aristotle had formed itself. This necessity is none other than the fact that the universal must now be proclaimed free for itself as the universality of the principle, so that the particular may be recognized through this universal; or the necessity of a systematic philosophy immediately enters in, what we formerly called one in accordance with the unity of the Notion. We may speak of the Platonic and Aristotelian systems, but they are not in the form of a system; for that it is requisite that one principle should be maintained and consistently carried through the particular. In the perfect complex of the conception of the universe as it is to Aristotle, where everything is in the highest form of scientific knowledge led back to what is speculative, however empiric may be his manner of setting to work, there certainly is one principle brought forward, and that a speculative one, though it is not brought forward as being one. The nature of the speculative has not been explicitly brought to consciousness as the Notion—as containing in itself the development of the manifold nature of the natural and spiritual universe, consequently it is not set forth as the universal, from which the particular was developed. Aristotle’s logic is really the opposite of this. He in great measure passes through a series of the living and the dead, makes them confront his objective, that is, conceiving thought, and grasps them in his understanding; each object is on its own account a conception which is laid open in its determinations, and yet he also brings these reflections together, and thereby is speculative. If even Plato on the whole proceeded in an empiric way, taking up this and that idea, each of which is in turn examined, with Aristotle this loose method of procedure appears still more clearly. In the Aristotelian teaching the Idea of the self-reflecting thought is thus grasped as the highest truth; but its realization, the knowledge of the natural and spiritual universe, constitutes outside of that Idea a long series of particular conceptions, which are external to one another, and in which a unifying principle, led through the particular, is wanting. The highest Idea with Aristotle consequently once more stands only as a particular in its own place and without being the principle of his whole philosophy.