“When the Lord taught us the doctrine of Father, Son, and Holy Spirit, he did not make arithmetic a part of this gift!” (On the Holy Spirit 18.44). Thus St Basil introduces a lengthy discussion of the numbering of the Trinity. Basil is contesting a simplistic numbering of the the divine hypostases that appears to terminate in tritheism. God has given us holy Names, not numbers, he declares. “The Unapproachable One is beyond numbers, wisest sirs … Count if you must, but do not malign the truth. Either honor Him Who cannot be described with your silence, or number holy things in accord with true religion. There is one God and Father, one Only-Begotten Son, and one Holy Spirit. We declare each Person to be unique, and if we must use numbers, we will not let a stupid arithmetic leads us astray to the idea of many gods” (18.44).
Basil then offers the following explanation:
If we count, we do not add, increasing from one to many. We do not say, “one, two, three,” or “first, second, and third.” God says, “I am the first and I am the last.” We have never to this present day heard of a second God. We worship God from God, confessing the uniqueness of the persons, while maintaining the unity of the divine Monarchy. We do not divide divine knowledge and scatter the pieces to the winds; we behold one Form (so to speak) united by the invariableness of the Godhead, present in God the Father and God the Only-Begotten. The Son is in the Father and the Father in the Son; what the Father is, the Son is likewise and vice-versa—such is the unity. As unique Persons, they are one and one; as sharing a common nature, both are one. How does one and one not equal two Gods? Because we speak of the emperor, and the emperor’s image—but not two emperors. The power is not divided, nor the glory separated. One is the dominion and authority over us; we do not send up glories to God, but glory; the honor given the image passes to the prototype. The image of the emperor is an image by imitation, but the Son is a natural image; in works of art the likeness is dependent on its original form, and since the divine nature is not composed of parts, union of the persons is accomplished by partaking of the whole. The Holy Spirit is one, and we speak of Him as unique, since through the one Son He is joined to the Father. (18.45)
When I first read this passage I thought that Basil was simply invoking the identity of the divine nature to rebut the charge of tritheism: “as sharing a common nature, both [the Father and Son] are one.” This is why all glory given to the Son, the natural image of the Father, immediately and naturally passes on to the Father, for the divine nature the Son possesses has been communicated to him by the Father and is identical to the divine nature of the Father. But Basil also seems to be saying that we cannot say that there are two (and by logical implication, three) hypostases: “As unique Persons, they are one and one.” Hold on, I thought. There’s the Father and the Son and the Spirit—doesn’t that add up to three hypostases? So I turned to John Behr’s exegesis of this passage for further help.
Behr reminds us that for St Basil “whatever is common to the the Father, Son, and Holy Spirit belongs to their common essence, while whatever is specific to each denotes their hypostasis” (The Nicene Faith, II:308). As Basil states in two of his letters:
If you ask me to state briefly my own view, I shall state that essence has the same relation to hypostasis as the common has to the particular. Every one of us both participates in being by the common term of essence, and by his own properties is such an one or such an one. So also here, the term “essence” is common, like goodness, or divinity, or any similar attribute; while the hypostasis is contemplated in the property of fatherhood, sonship or sanctifying power. (Ep 214.4)
The distinction between essence and hypostasis is the same as that between the general and the particular; as, for instance, between the animal and the particular human. Therefore, concerning the divinity, we confess one essence, so as not to give a differing principle of being; but the hypostasis, on the other hand, is particularizing, in order that our conception of Father, Son and Holy Spirit may be unconfused and clear. (Ep 236.6)
So if we are talking about animals in general, we would list everything that all animals share in common—this is their essence or substance. But if we are talking about one particular animal and of what separates it from all other animals, we refer to it by the word hypostasis. Basil proposes that we employ the words ousia and hypostasis along similar lines to speak of the Holy Trinity. Everything that the Father, Son, and Holy Spirit share in common, everything it means for God to be God, belongs to the divine ousia. But if we want to speak of either the Father, Son, or Holy Spirit in his particular existence, or if we want to speak of “them” in their mutual relationships, we use the word hypostasis.
Why then can we not add each divine hypostasis together to total three hypostases? Because if hypostasis denotes whatever is specific and particular to the Father, Son, or Spirit, it is impossible “to single out anything that is common to each hypostasis, as hypostasis, to facilitate counting ‘three,’ for, being common to the ‘three,’ it would have to be classified as belonging to their common essence. The divine hypostases can only be counted ‘singly’—one, and one, and one; or better, and this is clearly Basil’s preference, by using the divine names: Father, Son, and Holy Spirit” (Behr, II:308).
Commonsensically, of course, we do speak of three, and only three, divine persons. How can we not? We read the biblical narrative and we see three divine actors in the drama of salvation. We are baptized in the name of the Father, Son, and Holy Spirit. We invoke the “Holy Trinity” in the prayers of the Church, including the Divine Liturgy of Saint Basil the Great. But I suspect most of us have not noticed the oddity of our traditional language—three persons, one substance. How do we get to three if we can’t count? Beware of “stupid arithmetic.”