4) The three hypostases, the three different personae, could lead to tri-theism. This danger became much more fully real when the philosophy of Aristotle replaced that of Plato. Plato’s philosophy is always the background of what the medieval called mystical realism, namely that the universals are more real than their individual exemplars. But in Aristotle the thing is different: Aristotle calls the individual thing the telos, the inner aim, of all natural development. Now if this is the case, then the three powers of being in God become three independent realities – or more exactly, the three manifestations of God become independent powers of being, become independent persons This is something which I believe is one of the great difficulties in your understanding of the Trinitarian dogma. You are nominalists by education: everything which is must be a definite thing, limited and separated from all other things. For mystical, realistic thinking — as we have it in Plato, in Origen, in the Middle Ages – this is not so. There the power of being in a universal can be something quite superior and different from the power of being in the individuals.
Therefore the danger of tri-theism was very small, as long as Platonic philosophy interpreted the Trinitarian dogma. It became rather dangerous in the moment in which Aristotelian categories came in, and with it, some nominalistic trends, some emphasis on the individual realities. Then the Son and the Spirit could become, so to speak, special Individual beings – and then we are in the realm of tri-theism. The last great theologian, John of Damascus, of whom I hope Father Florovsky will tell you a little more, protested against this consequence. He emphasized the unity of action and being within each other of the three manifestations of God. But something else happened. For practical piety, the Trinitarian dogma became just the opposite of what it originally was supposed to be – it was supposed to be an interpretation of Jesus as the Christ; it was supposed to mediate this understanding to the Greeks, with the help of the Logos doctrine. But the consequences of the Logos doctrine became so dangerous in Arius especially, that traditional theology reacted against it. It was still used, but it was somehow broken in its philosophical meaning. And that’s something which has often happened with Christian theology.
In this way – and here Athanasius is mostly responsible – the Trinitarian dogma became a sacred mystery. This sacred mystery was put on the altar and adored; it was put into the ikons, the pictures (which are important for the cult in the Eastern church); it was put into liturgical formulas and hymns, and there it lives ever since. But it has lost its power to interpret the meaning of the living God.
Now this is the end of the Trinitarian struggle. I come back to it once more when I shall speak about Augustine’s interpretation of it, which is typically Western, but for the time being I will now introduce the next great struggle, the Christological one: The Christological problem is historically a consequence of the Trinitarian problem.