Against Eunomius, the extreme Arian, the last two of which are sometimes regarded as by another hand; an important work upon the Holy Spirit; Letters, which give a vivid picture of the writer's life and its surroundings; various ascetic works and sermons. The "Liturgy of St. Basil" and the "Liturgy of St. Chrysostom" subsequently used in the East were in all probability both based on an older liturgy that Basil used and gave to his clergy.
In defending the Nicene position Basil developed a new terminology which we may take as indicating some change of view. With Athanasius there is in God one ousia[1] (essence) or hypostasis[2] (substance), the two words being synonymous. But, according to Basil, while there is one ousia, there are three hypostases; and in this change of terminology the two Gregories agree, so that under the influence of the Cappadocian theologians it passes over into the language of the Greek Church. Meanwhile in the Latin Church there was no change of usage. Here it was taught all along that in the Trinity there was one substantia existing in three personæ.[3] But the Latin Church used the word substantia as equivalent to both the Greek words ousia and hypostasis. Thus the East saw three hypostases in the Trinity, but the West only one. The difference however was not so great as it appeared to be on the surface. The Greeks had no word equivalent to the Latin persona which they could use with safety, because the nearest corresponding term, prosopon,[4] was already appropriated in a Sabellian sense for a mere phase or aspect of God without any real distinction of person. Since the Arians were constantly charging the Nicene party with Sabellianism, it would never have done to adopt so suspicious a word. Accordingly a new term had to be found for what the West regarded as the personæ, literally the "characters" (as the word is used in a drama) of the Trinity, and
