Thus we have, in all, five gradations: the One, Nous, Soul, the sensible world, and, lastly, unformed Matter. Taken together, the first three constitute a triad of spiritual principles, and, as such, are associated in a single group by Plotinus.[467] Sometimes they are spoken of as the Alexandrian Trinity. But the implied comparison with the Trinity of Catholicism is misleading. With Neo-Platonism, the supreme unity is, properly speaking, alone God and alone One. Nous is vastly inferior to the first principle, and Soul, again, to Nous. Possibly the second and third principles are personal; the first most certainly is not, since self-consciousness is expressly denied to it by Plotinus. Nor is it likely that the idea of a supernatural triad was suggested to Neo-Platonism by Christianity. Each of the three principles may be traced to its source in Greek philosophy. This has been already shown in the case of the One and of the Nous. The universal soul is to be found in Plato’s _Timaeus_; it is analogous, at least in its lower, divided part, to Aristotle’s Nature; and it is nearly identical with the informing spirit of Stoicism. As to the number three, it was held in high esteem long before the Christian era, and was likely to be independently employed for the construction of different systems at a time when belief in the magical virtue of particular numbers was more widely diffused than at any former period of civilised history. From another point of view, as we have already observed with Kirchner, the fundamental triad assumed by Plotinus is body, soul, and spirit. Under their objective aspect of the sensible universe, the world-soul, and the Nous, these three principles constitute the sum of all reality. Take away plurality from Nous and there remains the One. Take away soul from body and there remains unformed matter. These are the two transcendent principles between which the others extend, and by whose combination in various proportions they are explained. It is true that Plotinus himself does not allude to the possibility of such an analysis, but it exhibits, better than any other, the natural order of his dialectic.