In his very first essay, Plotinus had hinted at a principle higher and more primordial than the absolute Nous, something with which the soul is connected by the mediation of Nous, just as she herself mediates between Nous and the material world. The notion of such a supreme principle was derived from Plato. In the sixth and seventh books of the _Republic_, we are told that at the summit of the dialectic series stands an idea to grasp which is the ultimate object of all reasoning. Plato calls this the Idea of Good, and describes it as holding a place in the intellectual world analogous to that held by the sun in the physical world. For, just as the sun brings all visible things into being, and also gives the light by which they are seen, so also the Good is not only that by which the objects of knowledge are known, but also that whence their existence is derived, while at the same time itself transcending existence in dignity and power.[454] In a former part of this work[455] we found reason to believe that Plato’s supreme good is no other than the Idea of Sameness which occurs in the _Sophist_ and in the _Timaeus_, where it is correlated with the Idea of Difference; and we also concluded that the divine creator of the last-named dialogue is intended to represent it under a more concrete and popular form.[456] We may, perhaps, also discover it in the Limit of the _Philêbus_; and if we are to believe what Aristotle tells us about the later teaching of Plato, it seems to have finally coalesced with the Pythagorean One, which combines with the unlimited Dyad to form first number, and then everything else, just as the Same combines with the Different to form existence in the _Timaeus_.[457] For the Platonic Idea of Good, Aristotle had substituted his own conception of self-thinking thought, as the absolute on which all Nature hangs: and we have seen how Plotinus follows him to the extent of admitting that this visible universe is under the immediate control of an incorporeal Reason, which also serves as a receptacle for the Platonic Ideas. But what satisfied Aristotle does not fully satisfy him. The first principle must be one, and Nous fails to answer the conditions of absolute unity, Even self-thinking thought involves the elementary dualism of object and subject. Again, as Plotinus somewhat inconsistently argues, Nous, being knowledge, must cognise something simpler than itself.[458] Or, perhaps, what he means is that in Nous, which is its product, the first principle becomes self-conscious. Consciousness means a check on the outflow of energy due to the restraining action of the One, a return to and reflection on itself of the creative power.[459]