Ousia

Ousia is the Greek word the Fathers used for what God is: the one divine being that the Father, the Son, and the Holy Spirit hold whole and in common. The same word names what any creature is, which is why the Fathers handled it with such care.

For Inquirers

Ask a person who they are and they will give you a name. Ask what they are and the answer changes: a human being, a person like you. The first answer belongs to them alone, and the second they share with everyone who has ever lived. The old Greek word for that second kind of answer is ousia (oo-SEE-ah), usually translated "essence," "being," or, in older books, "substance." It means what a thing most deeply is, the part of it that stays put while the rest of its story changes.

Christians reached for this word because of something they say about God that has no match in ordinary life. They say there is one God, and they say that the Father, the Son, and the Holy Spirit are each completely and truly God. The word lets them say it carefully: there is one divine being, one "what," and the Three are the ones who have it, each holding the whole of it. Think of three friends, each fully human, none of them holding a bigger or smaller piece of humanity than the others. The picture helps for a moment and then leaks, because friends can move to different cities and the Three can never be pulled apart, and Gregory the Theologian, as we will see, says as much about his own pictures.

Here the English word misleads. "Substance" sounds like stuff, something you could weigh or pour into a jar, and a good many of the old quarrels began with exactly that mistake. God is not made of anything. Basil and Chrysostom, whom the sections below follow, were just as firm that nobody can say what the divine ousia is like; the word stands over a depth we can point at and cannot see into. What a person can know is the God who comes near, who is known by what He does and gives, and worship begins there. Rome and the Eastern Fathers do not always say the same thing about what the word settles and what can be seen of it, as the section on East and West shows. The word itself is an old signpost at the edge of a very deep place.

Overview

Ousia (Greek οὐσία, "being," "essence," or in older English "substance") names what something is, the answer to "what is it?", as distinct from hypostasis, which names who someone is. After Basil's settlement the Church's formula is one ousia in three hypostases: one God, three Persons, though Nicaea's anathema had treated the two words as near-synonyms.
The word was at home in Greek schoolrooms before the Church used it, and Scripture does not use it as a name for God's being. A few writers used it before Nicaea, and in the fourth century its meaning was fought over for decades.
The First Council of Nicaea (325) confessed the Son "of the substance of the Father" and "of one substance" with Him, and condemned anyone who says He is "of a different substance or essence." Athanasius defended the word, and the Cappadocians fixed its partnership with hypostasis.
Basil, Chrysostom, and the Damascene teach that the divine ousia cannot be known: God is known by what He does and gives, and not by what it is to be God (Essence Energies).
Chalcedon uses the same word of the one Christ twice: He is "consubstantial with the Father" as to His Godhead and "consubstantial with us" as to His manhood.
Latin speakers rendered the word "substance." Gregory the Theologian and Basil both note that the two halves of the Church used the vocabulary differently, and the Latin and Eastern texts cited below part ways over the procession of the Spirit and over what the blessed will see.

Summary

What does the word "God" point at when Scripture uses it? Athanasius, arguing against men who wanted God's Fatherhood to be something merely about Him, answers that the plainest names Scripture gives God do not describe some attachment to God. They indicate Him: "But if God be simple, as He is, it follows that in saying 'God' and naming 'Father,' we name nothing as if about Him, but signify his essence itself." De Decretis 5.43[^dec22] The essence in that sentence is no layer beneath God and no part of Him. It is God, named without ornament. Athanasius adds in the same breath that to comprehend what this essence is remains impossible, and that it is enough to know that God is. De Decretis 5.44[^dec22b]

The word did not begin there. Augustine met it in a schoolbook, Origen and Tertullian used it before Nicaea, and Basil and Athanasius report that bishops at Antioch found fault with it in the case of Paul of Samosata. After Nicaea its meaning took decades of argument to fix. Athanasius defended it as the word that keeps the Son on God's side of the line between Maker and made. The Cappadocians, Basil, Gregory of Nyssa, and Gregory the Theologian, gave it a working partner, so that ousia named what the Three share and hypostasis named who each of the Three is. Homoousios and Hypostasis tell those two stories at length; the interest here is in the word they share.

If the Son is "of the essence" of the Father, the Church worships the Son; if He is only one of the things that came to be, it worships a creature. If the Three share one essence, the Church confesses one God; if each had his own, it would confess three. Two of the Eastern Fathers add a limit to both. Basil says that God's operations come down to us while His essence remains beyond our reach, and Chrysostom says that not even the angels have seen it. Rome's own texts speak differently: Aquinas and Benedict XII say that the blessed see the divine essence, and the section on East and West sets the two accounts side by side. For a word that Augustine first met in a schoolbook, it is asked to carry a great deal.

A Word from the Schoolroom

Ousia was a schoolroom word as well as a creed word. Augustine remembers meeting its Latin counterpart, "substance," as a young man in a book of Aristotle's that he knew as The Ten Predicaments, which he read without a teacher and thought he understood. By his account the book "appeared to me to speak plainly enough of substances, such as man is, and of their qualities." The Confessions — Book 4 16.4[^aug-cat] Everything that exists, on the scheme he describes, falls under one of ten headings, and substance is the chief of them; the other nine name what a substance has or does, such as how big it is, where it stands, and whom it is related to. A man is his example of a substance. How that schoolbook sense of "substance" relates to the way the Greek Fathers would later use ousia of God, Augustine does not say.

The borrowing carried a danger, and Augustine felt it in his own thinking. Believing that whatever existed had to be filed under one of the ten headings, he tried to think of God the same way, and the result was a picture of God as a being who has greatness and beauty the way a body has size and shape. Looking back, he writes: "imagining that whatsoever existed was comprehended in those ten categories, I tried so to understand, O my God, Your wonderful and unchangeable unity as if Thou also had been subjected to Your own greatness or beauty, so that they should exist in You as their subject, like as in bodies, whereas You Yourself art Your greatness and beauty." The Confessions — Book 4 16.6[^aug-cat2] The correction he arrived at, that God is His greatness and does not merely possess it, is the point Athanasius makes in the sentence that opens this entry: since God is simple, the names we give Him signify His essence itself.

A hostile witness describes another reader of the same book. Socrates the church historian says that Aëtius of Antioch, whose pupil Eunomius later led the Anomoean party, built his argument on Aristotle's Categories, a book whose scope Socrates says Aëtius never grasped, and that for this reason he "was unable to comprehend how there could be generation without a beginning, and how that which was begotten can be co-eternal with him who begot."[^soc235] The fault Socrates finds lies in Aëtius, a man of scanty instruction who mistook a schoolbook's sophisms for a rule, and he does not say that the book itself forbids an eternal begetting. Socrates counts Aëtius among the Arians even while reporting that the Arians expelled him, so his portrait is that of an opponent, and Aëtius's own reasoning reaches this entry only through Socrates and, below, through Gregory of Nyssa.

Scripture never says ousia of God, and Athanasius nonetheless argues that Nicaea's word fits what Scripture does say. Writing to the bishops of Africa about the council at Ariminum, he points to the name God gave Moses at the bush, which the Greek Old Testament renders "I am THE BEING" (Exodus 3.14), to Jeremiah's words about standing in God's "subsistence," and to Hebrews, where Paul calls the Son the "very image of his substance" (Hebrews 1.3). The Greek word in Hebrews is hypostasis, which the English Bible renders "substance" and Athanasius reads as "subsistence." From these texts he draws the equation: "now subsistence is essence, and means nothing else but very being." Ad Afros Epistola Synodica 4.7[^afros4] Those who will not speak of subsistence in God, he adds, speak like the fool who says in his heart that there is no God. On his reading, a schoolroom word and the words of the bush, of Jeremiah, and of Hebrews meet in the one idea of very being.

Before Nicaea

Before Nicaea the word turns up in a handful of writers whose texts survive, and each can be heard on his own terms. Origen, the Alexandrian teacher, speaks of the divine substance as something we cannot look at directly; his De Principiis survives chiefly in Rufinus's Latin, so the wording is a translator's. Our eyes cannot gaze on the sun's own substance, he says, but we can see its rays pour through a window, and in the same way "the works of Divine Providence and the plan of this whole world are a sort of rays, as it were, of the nature of God, in comparison with His real substance and being." De Principiis — Book I 1.47[^orig-rays] Basil, in Letter 234, later draws a similar line between God's works, which reach us, and His essence, which does not.

The Latin West was speaking of substance too. Tertullian, writing against a teacher who made the Father and the Son one and the same, holds the Three together by saying that they are "of one substance, and of one condition, and of one power, inasmuch as He is one God." Against Praxeas 2.7[^tert2] His sentence does a job that the Greeks would later give to ousia, though a single sentence cannot show how closely substantia in Tertullian matches the Greek word.

Origen's commentary on John, which survives in Greek, shows the word hypostasis in use before it had a fixed meaning. He writes that "We consider, therefore, that there are three hypostases, the Father and the Son and the Holy Spirit,"[^orig-hyp] using for the Three the very word that the fourth century would argue over. In the same passage he says that he believes nothing to be uncreated but the Father, and that the Holy Spirit is the most excellent and first in order of all that was made by the Father through Christ.

Athanasius preserves a letter of Dionysius, bishop of Rome, written against catechists and teachers who, as Dionysius had been told, preached in some sort three Gods, "dividing the sacred Monad into three subsistences foreign to each other and utterly separate." De Decretis 6.19[^dec26] In Dionysius's complaint, a word for the Three could sound like a division of God.

Athanasius also reports that Dionysius of Alexandria was accused of denying that the Son is homoousios with the Father, and quotes the defence in which Dionysius conceded the objection's strongest point. "For though I say that I have not found this term anywhere in Holy Scripture," he writes, "yet my remarks which follow… are not inconsistent with that belief." De Decretis 6.12[^dec25] He admitted that the word was not biblical, and argued that the belief behind it was.

There was also a reason the word had a bad name among bishops. Basil reports that the members of the synods which met to consider the case of Paul of Samosata found fault with the term as an unfortunate one,[^b52a] and Athanasius records the argument Paul had pressed: "Unless Christ has of man become God, it follows that He is Coessential with the Father; and if so, of necessity there are three essences, one the previous essence, and the other two from it." De Synodis 45.6[^syn45] On Athanasius's account the bishops who deposed Paul took the word in a bodily sense, with some common stuff lying behind both Father and Son, and guarded against it by saying that Christ was not coessential. Those bishops were not contradicting the bishops who later enthroned the word, Athanasius says, since "the one party condemned the Samosatene, while the other condemned the Arian heresy," De Synodis 45.3[^syn45b] and each wrote suitably to the matter at hand.

The Word in the Creed

The creed of 325 uses the word at three points. It says that the Son is "of the substance of the Father" and "of one substance" with the Father The Nicene Creed 1.1 and, at the end, it anathematizes those who say that "he is of a different substance or essence [from the Father]." The Nicene Creed 1.7[^creed] Two nouns are paired in that last clause, and for some decades afterward the Greek words for "essence" and "subsistence" could be used as the same thing; Athanasius himself, defending the creed, treats them so.[^afros4b]

What "of the substance" was meant to rule out, Athanasius explains with a clear head. Scripture says that all things are "from God," and the Arian party could say it of the Son and mean no more than they meant of the rest of creation. The bishops, seeing this, wrote that the Son is from God's essence so that "we might believe the Word to be other than the nature of things originate, being alone truly from God." De Decretis 5.16[^dec19] Nothing a creature can be said to have from God is what the Son has from the Father. In Athanasius's terms the Son is the Father's offspring and so has the Father's own being, while creatures are His works. Athanasius presses the point a second way: the very word "God" in Scripture signifies "the very simple, and blessed, and incomprehensible essence itself," De Synodis 35.3 so that anyone who grants the Son is "from God" has already granted that He is from the essence.[^syn35]

Eusebius of Caesarea, who signed the creed, explained to his church why. He says that the phrases were examined by question and answer, and that it was agreed "ousias (of the essence or substance) simply implied that the Son is of the Father indeed, but does not subsist as a part of the Father."[^euseb] The sense agreed in the discussion Eusebius records, then, is that the Son is of the Father with no cutting and no portioning in it.

The men who had been deposed at Ariminum, Athanasius reports, ventured to write that it ought not to be said that the Son had essence or subsistence at all, and he answers them with Scripture and the burning bush.[^afros4c] Those who proposed "like in essence" in its place, whom OrthodoxWiki calls the semi-Arian party, he treats more gently, since they confessed the Son to be "of the essence" and so had come most of the way; he tells them that to say only "like according to essence" is "very far from signifying 'of the essence.'" De Synodis 41.4[^syn41] The detail of that debate belongs to Homoousios and Arianism, and what matters here is that every stage of it was a fight over what ousia meant.

Stuff or Kind

The word's real difficulty, then as now, was that it sounds like a material. The Latin bishop Hilary of Poitiers set down the objections to homoousios that were in circulation in his day, and one of them is that the word implies "a certain imaginary substance, or ousia, anterior to all matter whatsoever, has existed heretofore and been divided and wholly distributed between the Two." On the Trinity 4.32[^hil-trin] A listener who hears ousia as raw material will picture the Father and the Son as two portions of one stock, or as two heirs to a prior estate, and the picture gives the Father the shape of a body.

Basil answers the same worry in a letter meant to settle suspicions about his own faith. The old synod, he says, found the word troublesome because it was read that way: "This explanation has some reason in the case of bronze and coins made therefrom, but in the case of God the Father and God the Son there is no question of substance anterior or even underlying both." Letters (St. Basil of Caesarea) — Letter 52 1.13[^b52] Coins are struck from a common stock of bronze, which comes before every coin. Between the Father and the Son there is no bronze, and nothing stands behind either of them. Hilary grants that the word can be misused and gives the rule for using it well: the one substance must be derived "from the true character of the begotten nature," and never from a division of God, a confusion of Persons, or a sharing of an earlier substance.[^hil-syn]

John of Damascus answers the misreading from the other side, by saying what the one essence is not made of. He says that each of the Three is perfect in his own subsistence so that "we may understand not one compound perfect nature made up of three imperfect elements, but one simple essence, surpassing and preceding perfection, existing in three perfect subsistences." An Exposition of the Orthodox Faith — Book I 8.73[^dam-compound] To see what he is excluding, take a house: stone, wood, and iron are each perfect of their kind and still are not a house, and the Three are nothing like that, for each of them is the whole of God. And the essence is never found anywhere except in them. The Damascene says plainly that "there is no nature without subsistence, nor essence apart from person (since in truth it is in persons and subsistences that essence and nature are to be contemplated)." An Exposition of the Orthodox Faith — Book Iii 9.1[^dam-9] A reader who goes looking for the divine ousia as something that could be met on its own, behind the Persons, is looking for what the Damascene says does not exist.

One Ousia, Three Hypostases

The creed of 325 had spoken of one "substance or essence" and left unsettled how the Three were to be named, and the next fifty years went to that. A scene that OrthodoxWiki's timeline dates to 362, the Synod of Alexandria, shows how thin the margin was. Athanasius, with the bishops present in Alexandria, questioned two groups of Christians who had been accusing each other of heresy, one that spoke of three hypostases and one that spoke of one. The first, asked whether they meant three alien essences or three gods, said they did not. The second said, of their own word, "we use the word Subsistence thinking it the same thing to say Subsistence or Essence," Tomus ad Antiochenos 6.3 and added that they meant one because the Son is of the Father's essence.[^tomus] Both groups confessed Nicaea, and the bishops decided that they were not far apart. Pomazansky, a modern Orthodox dogmatician writing of the early period in general, describes the same pattern: ousia was understood in much the same way by everyone, the confusion came from hypostasis, which some used for the Persons and others for the essence, and the authoritative example of Basil settled it.[^pom]

Basil gave the settlement its lasting form. Writing to Amphilochius, he says that the distinction between ousia and hypostasis is the one between the general and the particular, "as, for instance, between the animal and the particular man," Letters (St. Basil of Caesarea) — Letter 236 6.1[^b236] and from it he draws a rule for confessing the faith: the believer says "I believe in God the Father," adding the particular to the common, and then in God the Son, and in God the Holy Spirit. In Basil's own words, "The Godhead is common; the fatherhood particular." Letters (St. Basil of Caesarea) — Letter 236 6.5 Those who identify the two words, he warns, are compelled to confess only three Persons while hesitating to say three hypostases, and so fall short of escaping Sabellius, for whom one hypostasis changed its form as the occasion required. A short treatise preserved among Basil's letters as Letter 38, addressed "To his Brother Gregory," works the same distinction through the names "man" and "Paul," which Hypostasis follows at length; its authorship is uncertain, and some modern scholars assign it to Gregory of Nyssa.[^b38] In the account Basil gives Amphilochius, the word ousia is the common ground, and the Persons are the ones who stand on it.

Gregory the Theologian said the same thing in his own voice and gave it a sentence that has stayed the plainest summary: "the Godhead is, to speak concisely, undivided in separate Persons; and there is one mingling of Light, as it were of three suns joined to each other." Select Orations — Oration 31 0.162[^n31-14] When he looks at the Godhead or the First Cause, he says, what he conceives is one, and when he looks at the Persons in whom the Godhead dwells, there are three whom he worships. He insisted that the vocabulary was a servant. Pressed by quarrelsome people over whether to say three hypostases or three persons, he asks the first party whether they mean three essences and the second whether they mean a single being with three faces, says he is sure that each would loudly refuse the meaning he names, and concludes that the disagreement lies only in the syllables.[^n42]

A correspondent named Ablabius put the hardest question to Gregory of Nyssa. He pointed out that Peter, James, and John, sharing one human nature, are called three men, and asked why the same logic does not make the Father, the Son, and the Spirit three Gods. Gregory's first answer is bold. The ordinary practice of speaking of many men is, strictly, "a customary abuse of language," since the man in all of them is one, and a more careful speaker would never extend the name of the nature into the plural. On Not Three Gods 0.12[^nyssa-abl] The habit is too strong to correct where little harm follows from it, he admits, and too dangerous to indulge when speaking of God; so Scripture's testimony stands that there is one God, even though the name of Godhead extends through the Trinity.

Among men, three orators plead three separate cases, and so they are rightly counted as three. In God, he says, no work belongs to one Person apart from the others: "every operation which extends from God to the Creation… has its origin from the Father, and proceeds through the Son, and is perfected in the Holy Spirit." On Not Three Gods 0.53[^nyssa-op] What creation receives comes as one working of the Three, and not as three separate gifts. What distinguishes the Persons, he adds, is the manner of their origin: one is the Cause and another is of the Cause, and among those who are of the Cause, one is directly from the first Cause and another is through Him who is directly from it. That difference in how each exists leaves what each is untouched.[^nyssa-mode] A plural count of Gods would need a division of working, Gregory answers, and the single working of the Three allows none.

Gregory the Theologian and the Damascene admit the limits of the human picture. Gregory offers Adam, Eve, and Seth as three who share one humanity, and then says at once that no image can be traced out "exactly to the whole extent of the truth." Select Orations — Oration 31 0.117[^n31-11] The Damascene says where the picture breaks. In creation the individuals are visibly separate and their common nature is grasped by thought, but in the Trinity it is the reverse: "for there the community and unity are observed in fact, through the co-eternity of the subsistences." An Exposition of the Orthodox Faith — Book I 8.97[^dam-fact] Three friends are really three, and the humanity they share is something the mind sees in them. The Father, the Son, and the Spirit are really one God, and the distinction among them is what thought has to pick out.

The Essence No One Sees

Basil, Chrysostom, and the Damascene, each in his own way, say that no one has looked into what the word names. Basil takes it up directly in Letter 234, to Amphilochius. His opponents had asked him whether he worshipped what he knew or what he did not, and went on to demand the essence of the object of worship, so that any admission of ignorance could be turned into an accusation of blind worship. Basil answers by distinguishing kinds of knowing: we know God's greatness and power and goodness and providence, but not His very essence.[^b234] He turns to John 1.18, "No one has seen God at any time. The only born Son, who is in the bosom of the Father, has declared him," and asks what the Son declared, the essence or the power, and where in Scripture the Son ever said that the essence was unbegottenness. He puts his conclusion in a sentence: "His operations come down to us, but His essence remains beyond our reach." Letters (St. Basil of Caesarea) — Letter 234 0.20

Chrysostom reads the Old Testament visions in the same direction. Preaching on that verse, he raises Isaiah, Ezekiel, Daniel, Moses, and Jacob, who all saw something, and concludes that "all these were instances of (His) condescension, not the vision of the Essence itself unveiled." Homilies on the Gospel of John — Homily 15 1.23[^chrys15] If they had seen the very nature, he reasons, they would not have seen it in different forms, since it is simple and has no parts or shape. What God really is, he says, not even angels and archangels have seen. He cites Paul, who writes of God that "no man has seen nor can see" (1 Timothy 6.16), and asks how a created nature could see the Uncreated. Homilies on the Gospel of John — Homily 15 1.34[^chrys15b] The reason he gives is the difference between a created nature and the Uncreated.

The Damascene says the same in the language of the schools and takes it a step further. "He does not belong to the class of existing things," he writes of God; "not that He has no existence, but that He is above all existing things, nay even above existence itself." An Exposition of the Orthodox Faith — Book I 4.25[^dam4] All knowledge has to do with what exists, he reasons, and so what is above knowledge must also be above essence. The word that began as the schoolroom term for what a thing is turns out, when it is spoken of God, to be a word the Damascene uses and then leans past: God's essence is real, it is what God is, and it exceeds the reach of every category the word was made for.

Against this stood a position that Gregory of Nyssa reports in his answer to Eunomius, the pupil of Aëtius who led the Anomoean party after him.[^anomoean] As Gregory reports him, Eunomius started from God's simplicity, reasoning that a simple being has nothing in it that is not its essence, so that "Ungenerate," his preferred title for the Father, must be the essence itself; and since the Son is generate, His essence must differ. Eunomius's own writings are not quoted here, and this is his opponent's account of his argument. Gregory charges that Eunomius's party "declare ungeneracy to be His essence, in order that by this distinction in regard to generation they may establish, by the verbal opposition, a diversity of natures." Answer to Eunomius' Second Book 0.77[^nyssa-eun] On Gregory's account a single title was being asked to name the whole of God, and the title happened to exclude the Son. Basil, answering the demand to say what the essence is, retorts that "If you say that you know His essence, you are ignorant of Himself." Letters (St. Basil of Caesarea) — Letter 234 2.2

Gregory Palamas, centuries later, says that an essence never exists apart from what it does: "Unless an essence has an energy distinct from itself, it will entirely lack actual existence and will be a mere mental concept." Topics of Natural and Theological Science 136[^pal136] The remark sounds like the Damascene's point that essence is found only in persons, and it sits beside Palamas' flat statement that no creature can participate in the essence of the Creator.[^pal94] How the unknown essence and the known energies stand to each other is taken up in Essence Energies and Created vs Uncreated Grace, and Basil's sentence about operations coming down to us is already the shape of it.

Simple, and Not Made

Athanasius, answering anyone who made the Father's Fatherhood an accident attached to His essence, says that such a person makes God corporeal and falsely makes the Son the Son of something about God rather than of God, and that if God is simple, to name Him is to name His essence and nothing around it.[^dec22c] Augustine's confession in the schoolroom section was the same recognition reached from the other direction, and Basil makes it the ground of his reply to those who say God's attributes are His essence: "The operations are various, and the essence simple." Letters (St. Basil of Caesarea) — Letter 234 0.19[^b234b] Whether a real distinction between what God is and what God does compromises that simplicity is the question Essence Energies takes up at length, at length.

A creature has no essence of its own that was there before it, and Athanasius says so in his account of the creation of man: "For man is by nature mortal, inasmuch as he is made out of what is not." On the Incarnation of the Word 4.15[^inc4] What a creature is was given to it out of nothing, and it was called into being by the loving-kindness of the Word. The gift did not stop at being: "For God has not only made us out of nothing; but He gave us freely, by the Grace of the Word, a life in correspondence with God." On the Incarnation of the Word 5.1[^inc5] The creature's essence is a gift with nothing under it, and the Creator's is the being from which the gift comes.

That difference underlies the Damascene's account of begetting and making. When the Father begets the Son, he says, "the begetter produces out of his essence offspring similar in essence," An Exposition of the Orthodox Faith — Book I 8.15 and when God creates, the Maker works from outside Himself and brings into being a thing "of an absolutely dissimilar nature." An Exposition of the Orthodox Faith — Book I 8.16[^dam-gen] So the word ousia carries the line between Creator and creature, and the whole fight over the Son's essence was a fight over which side of that line to put Him on. The Damascene then notes that Greek has two near-identical words, one spelled with a single n meaning "uncreated" and one with a double n meaning "unbegotten," and that in the first sense there is one uncreated essence and a created one, while in the second the three Persons differ only in how each has His origin.[^dam-agen] The Father, the Son, and the Spirit share the one uncreated essence, and the sea, the stars, and the angels do not.

Two Natures, One Person

Nicaea's word came back in the next century with a second object. The Council of Chalcedon, in its Definition of Faith, confessed Him "consubstantial with the Father as touching his Godhead, and consubstantial with us as touching his manhood." The Definition of Faith 8.1[^chalc] The same Greek word is applied to the one Lord in two directions. In the first it says that He has the Father's own being, and in the second that He has ours, as truly as any of us does, sin alone excepted. The Church had settled what the Son shares with the Father at Nicaea, and Chalcedon says what He shares with us.

The Damascene shows how the vocabulary of the Trinity carries over into Christ. "For Godhead implies nature, while Father implies subsistence," he writes, "just as Humanity implies nature, and Peter subsistence." An Exposition of the Orthodox Faith — Book Iii 11.28[^dam11] The incarnate Word has taken a human nature into His own subsistence, and so it is the same who who is God and man. Each of the two natures keeps its own properties, as Chalcedon has it, and the one who holds them both is a Person. The question of who that Person is belongs to Hypostasis and Prosopon, and what the union opens up for those who are joined to Him belongs to Theosis.

East and West

The Latin and Greek halves of the Church did not always use these words the same way, and Gregory the Theologian and Basil both say so. Gregory, praising Athanasius for settling a quarrel over exactly this point, describes the situation lightly: "We use in an orthodox sense the terms one Essence and three Hypostases, the one to denote the nature of the Godhead, the other the properties of the Three; the Italians mean the same, but, owing to the scantiness of their vocabulary, and its poverty of terms, they are unable to distinguish between Essence and Hypostases, and therefore introduce the term Persons, to avoid being understood to assert three Essences." Select Orations — Oration 21 35.6[^n21] Each side then suspected the other, he says, Sabellianism in "three Persons" and Arianism in "three Hypostases," and the world came near to being torn asunder over syllables. Basil makes a related observation to Count Terentius, that the Westerners themselves feel the gap in their language and for that reason keep the Greek word ousia in their writing, so that the difference of meaning can be preserved.[^b214]

The Latin word for ousia was "substance" (substantia), and several texts show the equation. A formula issued at Sirmium, which Hilary of Poitiers preserved in order to answer it, forbids any more discussion of "questions concerning substance, called in Greek οὐσία," and of the words homoousion and homoiousion that go with it.[^hil-syn11] Hilary himself glosses "of one substance" as the Greek homoousion,[^hil-trin2] and the Latin version of the Nicene creed carries the Greek word as consubstantialem.[^creed2] When the bishops at Constantinople wrote in 382 to the bishops assembled at Rome, they gave the faith in both vocabularies at once: "there is one Godhead, Power and Substance of the Father and of the Son and of the Holy Ghost; the dignity being equal, and the majesty being equal in three perfect hypostases, i.e. three perfect persons." Synodical Letter 1.25[^syn382b] The gloss "i.e. three perfect persons" sets the Greek hypostases beside the word Latin readers used.

The procession of the Holy Spirit is where the Latin texts and the Eastern Fathers cited here part ways over what the one essence settles. Thomas Aquinas argues that the divine Persons are distinguished from one another only by their relations, because anything said of God absolutely belongs to the unity of the one essence, and that relations can distinguish Persons only if they are opposite; since the Son and the Spirit would not be distinguished unless one stood to the other as from a source, he concludes that the Spirit proceeds from the Son.[^aq-36-2] He holds in the same place that "The Father and the Son are in everything one, wherever there is no distinction between them of opposite relation," and therefore that they are one principle of the Spirit.[^aq-36-4] His argument runs from the unity of the essence to a conclusion about where the Persons come from.

The Council of Florence, in its decree for the Greeks, defines that the Holy Spirit "has His essence and His subsistent being both from the Father and the Son, and proceeds from both eternally as from one principle and one spiration."[^florence] The ground the decree states is different from Aquinas's, and it rests on what the Father gives: "since all that the Father has, the Father himself, in begetting, has given to His only begotten Son, with the exception of Fatherhood, the very fact that the Holy Spirit proceeds from the Son, the Son himself has from the Father eternally." The same decree reads the Fathers' "from the Father through the Son" to mean that the Son also is the cause, as the Greeks say, or the principle of the subsistence of the Spirit, as the Latins say.

The Eastern Fathers cited here put the weight elsewhere. The Damascene writes that "we do not speak of the Spirit as from the Son: but yet we call Him the Spirit of the Son. … And we confess that He is manifested and imparted to us through the Son." An Exposition of the Orthodox Faith — Book I 8.122[^dam-spirit] The Spirit is the Son's Spirit, on this reading, and is shown and given through Him, while the same passage speaks of the Spirit as from the Father. Aquinas knows the Damascene's sentence. He cites it as an objection in the same article and replies that on this point the Damascene's opinion is not to be held, while noting that some say the words do not amount to a denial.[^aq-36-obj]

Letter 38, preserved among Basil's letters, says that God alone has, as one special mark of His own hypostasis, His being Father and "deriving His hypostasis from no cause." Letters (St. Basil of Caesarea) — Letter 38 4.11[^b38b] Gregory of Nyssa, writing to Ablabius, grounds the difference of the Persons in one being the Cause and another being of the Cause, and adds that of those who are of the Cause one is directly from the first Cause and another by that which is directly from the first Cause.[^b38-cause] The Latin texts above reason from the relations and from what the Father gives to the Son, and the Eastern texts speak of the Father as cause and of the Son as the one through whom the Spirit is shown and given. Whether these are two accounts of the same fact is what The Filioque and Monarchy of the Father take up at length.

Aquinas teaches that God is the same as His essence and altogether simple, with no composition of any kind,[^aq-3] and that the blessed see that essence: "Hence it must be absolutely granted that the blessed see the essence of God."[^aq-12] The first objection in that article is a passage of Chrysostom on the same verse of John, in which not even angels and archangels have seen God, and Aquinas answers that both authorities he cites there speak of a comprehending vision. Benedict XII's constitution of 1336 defines that the souls of the blessed see the divine essence "with an intuitive vision and even face to face, without the mediation of any creature by way of object of vision; rather the divine essence immediately manifests itself to them, plainly, clearly and openly."[^bxii] On the Eastern side Chrysostom says that no created nature, angels included, can see the Uncreated essence, and Palamas says that no one can participate in the essence of the Creator. Whether the two accounts contradict each other, or measure the same unreachable thing in different ways, is the debate that Essence Energies and Created vs Uncreated Grace pursue with the Latin texts in front of them.

Why the Word Still Matters

What God is, is wholly given in the Father, the Son, and the Holy Spirit. The word secures the confession that the one who became man is God and that the Three are one God. It also carries a caution, which the Eastern Fathers press and Rome states in its own terms, that no sentence about God exhausts Him and that a Greek word has not put Him on a shelf. A Christian who prays to the Father through the Son in the Spirit is praying to the one whose being the Son and the Spirit share whole and undivided. That is why Homoousios and Hypostasis each need the other, and why the confession of The Trinity and the doctrine of the essence and energies both begin from what this one word can say and what it must leave unsaid.

Sources

[^dec22]: Athanasius, De Decretis (Defence of the Nicene Definition) 22. [^dec22b]: Athanasius, De Decretis 22. [^aug-cat]: Augustine, Confessions 4.16.28. [^aug-cat2]: Augustine, Confessions 4.16.29. [^soc235]: Socrates Scholasticus, Ecclesiastical History 2.35. [^afros4]: Athanasius, Ad Afros Epistola Synodica 4. [^orig-rays]: Origen, De Principiis 1.1.6 (in Rufinus's Latin translation). [^tert2]: Tertullian, Against Praxeas 2. [^orig-hyp]: Origen, Commentary on the Gospel of John, Book 2. [^dec26]: Athanasius, De Decretis 26, quoting Dionysius of Rome. [^dec25]: Athanasius, De Decretis 25, quoting Dionysius of Alexandria; compare De Synodis 44. [^b52a]: Basil, Letter 52.1. [^syn45]: Athanasius, De Synodis 45. On the Antioch synod's treatment of Paul of Samosata see also OrthodoxWiki, "Paul of Samosata." [^syn45b]: Athanasius, De Synodis 45. [^creed]: Council of Nicaea (325), Creed and anathemas (Percival translation). [^afros4b]: Athanasius, Ad Afros Epistola Synodica 4; Tomus ad Antiochenos 6. [^dec19]: Athanasius, De Decretis 19. [^syn35]: Athanasius, De Synodis 35. [^euseb]: Eusebius of Caesarea, letter to his church, in Socrates Scholasticus, Ecclesiastical History 1.8. [^afros4c]: Athanasius, Ad Afros Epistola Synodica 4. [^syn41]: Athanasius, De Synodis 41; on the semi-Arian party see OrthodoxWiki, "Semi-Arianism." [^hil-trin]: Hilary of Poitiers, On the Trinity 4.4. [^b52]: Basil, Letter 52.1. [^hil-syn]: Hilary of Poitiers, On the Councils (De Synodis) 71. [^dam-compound]: John of Damascus, An Exact Exposition of the Orthodox Faith 1.8. [^dam-9]: John of Damascus, An Exact Exposition of the Orthodox Faith 3.9. [^tomus]: Athanasius and the bishops at Alexandria, Tomus ad Antiochenos 5–6; for the date see OrthodoxWiki, "Timeline of Church History (Nicene Era (325-451))." [^pom]: Michael Pomazansky, Orthodox Dogmatic Theology, Part I, "The Oneness of Essence, the Equality of Divinity, and the Equality of Honor of God the Son with God the Father." He does not discuss the Alexandrian synod. [^b236]: Basil, Letter 236.6. [^b38]: Letter 38.2–3, preserved among Basil's letters. [^n31-14]: Gregory the Theologian, Oration 31.14. [^n42]: Gregory the Theologian, Oration 42.16. [^nyssa-abl]: Gregory of Nyssa, To Ablabius: On "Not Three Gods." [^nyssa-op]: Gregory of Nyssa, To Ablabius: On "Not Three Gods." [^nyssa-mode]: Gregory of Nyssa, To Ablabius: On "Not Three Gods." [^n31-11]: Gregory the Theologian, Oration 31.11. [^dam-fact]: John of Damascus, An Exact Exposition of the Orthodox Faith 1.8. [^b234]: Basil, Letter 234.1–3. [^chrys15]: John Chrysostom, Homilies on the Gospel of John 15. [^chrys15b]: John Chrysostom, Homilies on the Gospel of John 15. [^dam4]: John of Damascus, An Exact Exposition of the Orthodox Faith 1.4. [^anomoean]: OrthodoxWiki, "Anomoeanism" and "Aëtius of Antioch." [^nyssa-eun]: Gregory of Nyssa, Answer to Eunomius' Second Book. [^pal136]: Gregory Palamas, Topics of Natural and Theological Science and on the Moral and Ascetic Life 136, in the Philokalia. [^pal94]: Gregory Palamas, Topics of Natural and Theological Science and on the Moral and Ascetic Life 94, in the Philokalia. [^dec22c]: Athanasius, De Decretis 22. [^b234b]: Basil, Letter 234.1. [^inc4]: Athanasius, On the Incarnation of the Word 4. [^inc5]: Athanasius, On the Incarnation of the Word 5. [^dam-gen]: John of Damascus, An Exact Exposition of the Orthodox Faith 1.8. [^dam-agen]: John of Damascus, An Exact Exposition of the Orthodox Faith 1.8. [^chalc]: Council of Chalcedon (451), Definition of Faith. [^dam11]: John of Damascus, An Exact Exposition of the Orthodox Faith 3.11. [^n21]: Gregory the Theologian, Oration 21.35. [^b214]: Basil, Letter 214.4. [^hil-syn11]: Hilary of Poitiers, On the Councils (De Synodis) 11, preserving the Sirmium formula. [^hil-trin2]: Hilary of Poitiers, On the Trinity 4.4. [^creed2]: Council of Nicaea (325), Creed (Percival translation, which gives the Latin consubstantialem). [^syn382b]: Synod of Constantinople (382), Synodical Letter to the bishops assembled at Rome. [^aq-36-2]: Thomas Aquinas, Summa Theologiae I q.36 a.2 co. [^aq-36-4]: Thomas Aquinas, Summa Theologiae I q.36 a.4 co. [^florence]: Council of Florence, Decree for the Greeks (Laetentur Caeli, 1439), DS 691. [^dam-spirit]: John of Damascus, An Exact Exposition of the Orthodox Faith 1.8. [^b38b]: Letter 38.4, preserved among Basil's letters. [^b38-cause]: Gregory of Nyssa, To Ablabius: On "Not Three Gods." [^aq-36-obj]: Thomas Aquinas, Summa Theologiae I q.36 a.2, obj. 3 and ad 3. [^aq-3]: Thomas Aquinas, Summa Theologiae I q.3 aa.3 and 7. [^aq-12]: Thomas Aquinas, Summa Theologiae I q.12 a.1, co, obj. 1, and ad 1. [^bxii]: Benedict XII, Constitution Benedictus Deus (1336), the definition on the vision of the souls of the blessed.