It was only gradually that the subject was raised to the higher plane, from which it never afterwards descended, by the spread and dominance of the transcendental as distinguished from the supra-cosmic conception of God. It came, as we have already seen, mainly from the schools of Alexandria. It is in Basilides, in whom thought advanced to the belief that God transcended not merely phenomena but being, that the conception of a quasi-physical influence emanating from Him is seen to be first expressly abandoned.[546] But the place of the later doctrine in the Christian Church is mainly due to Origen. He uses many of the same expressions as Tertullian, but with another meaning. The Saviour is God, not by partaking, but by essence.[547] He is begotten of the very essence of the Father. The generation is an outflow as of light from light.
But the controversies did not so much end with Origen as begin with him. From that time they were mostly internal to Christianity. But their elements were Greek in origin. The conceptions which were introduced into the sphere of Christian thought were the current ones of philosophy. In Christian theology that philosophy has survived.
But although it would be beyond our present purpose to describe the Christological controversies which followed the final dominance in the Church of the transcendental idea of God, it is within that purpose to point out the Greek elements, confining ourselves as far as possible to the later Greek uses of the terms.
Ousia (οὐσία) is used in at least three distinct senses: the distinction is clearly phrased by Aristotle.[548]
(a) It is used as a synonym of hylê, to designate the material part of a thing. The use is most common among the Stoics. In their monistic conception of the universe, the visible world was regarded as the ousia of God.[549] In the same way Philo speaks of the blood as the material vehicle, τὸ οὐσιῶδες, of the vital force.[550] Hence in both philosophical and Christian cosmologies, ousia was sometimes used as interchangeable with hylê, to denote the matter out of which the world was made.
(b) It is used of matter embodied in a certain form: this has since been distinguished as the substantia concreta. In Aristotle, a sensible material thing, a particular man or a particular horse, which in a predication must always be the subject and cannot be a predicate, is an ousia in the strictest sense.[551]
(c) It is used of the common element in the classes into which sensible material things may be grouped: this has since been distinguished as the substantia abstracta: in the language of Aristotle, it was the form (εἶδος), or ideal essence (τὸ τί ἦv εἶναι).[552] This sense branched out into other senses, according as the term was used by a realist or a nominalist: to the former it was the common essence which exists in the individual members of a class (τὸ εἶδος τὸ ἐνόν),[553] and not outside them (since ἀδύνατον χωρὶς εἶναι τὴν οὐσίαν καὶ οὗ ἡ οὐσία);[554] or which exists outside them, and by participation in which they are what they are: this latter is Plato’s conception of εἶδος,[555] and of its equivalent οὐσία.
To a nominalist, on the other hand, ousia is only the common name which is predicable in the same sense to a number of individual existences.[556]
The Platonic form of realism grew out of a distinction between the real and the phenomenal, which in its turn it tended to accentuate. The visible world of concrete individuals was regarded as phenomenal and transitory: the invisible world of intelligible essences was real and permanent: the one was genesis, or “becoming;” the other, ousia, or “being.”[557] The distinction played a large part in the later history of Platonism:[558] and whereas in the view of Aristotle the species, or smaller class, as being nearer to the concrete individuals, was more ousia than the genus, or wider class, in the later philosophy, on the contrary, that was ousia in its highest sense which was at the farthest remove from the concrete, and filled the widest sphere, and contained the largest number of other classes in itself: it was the summum genus.[559] Hence Plotinus says that in respect of the body we are farthest from ousia, but that we partake of it in respect of our soul; and our soul is itself a compound, not pure ousia, but ousia with an added difference, and hence not absolutely under our control.[560]