31 March 2018

Ousía and hypostasis from the philosophers to the councils

Abstract

During the IV to VI centuries, the Christian doctrine of the Trinity was formulated using primarily three Greek terms: ousía, hypostasis and prósōpon. Of those, hypostasis is unique for two reasons: first, it is the only one present in the NT (Heb 1:3), and secondly, it was used successively in two mutually incompatible senses: in Nicaea as synonym of, and to provide precision for, ousía, and from the Cappadocian Fathers onwards as synonym of, and to provide precision for, prósōpon. In this article I will examine the introduction of the terms ousía and hypostasis in the Greek philosophical discourse and the development of their meaning, focusing on the meaning of hypostasis which was current at the time when Heb 1:3 was written, the issues at play in the Christian doctrine of the Trinity, and the use by the Church of the terms ousía, hypostasis and prósōpon to provide a precise formulation of that doctrine.


Table of contents

1. Plato and Aristotle: what is primary ousía?
2. Enter hypostasis, the original cognate of substantia.
3. Hebrews 1:3 in a Stoic and Epicurean lexical context.
4. Trinitarian orthodoxy and the three possible ways to fall from it.
5. The "one ousía" answer to Arianism, its modalistic and tritheistic risks, and Nicaea's "one hypostasis" as prevention of the second.
6. The three Hypostases formula: appearance, toleration by St. Athanasius, resistance by St. Jerome, and my argument for it.
7. The three Hypostases formula: proposal by St. Basil and St. Gregory of Nyssa and increasingly official Church adoption since 382.
8. Post-Chalcedon problem A: ambiguity in ousía or in homoousios.
9. Post-Chalcedon problem B: why is it that Jesus' objective, concrete, really existing human nature is not a hypostasis?
References


1. Plato and Aristotle: what is primary ousía?

The etymological chain of origin of ousía is:

eimí: to be, to exist (first person singular) [1];

ōn: present participle of eimí (masculine nominative singular) [2];

oûsa: feminine nominative singular of ōn [3] = feminine nominative singular present participle of eimí;

ousíā: derivative noun of oûsa [4];

ousía: modern form of ousíā [5].

Deriving then from the verb "to be", as we can see in [4] ousía enters the Greek philosophical discourse with Plato, who uses it to mean the primary, fundamental kind of being, ("prōtē ousíā", pl. "prôtai ousíai"), with Aristotle afterwards using it with the same meaning. It is crucial to note that, for both Plato and Aristotle, ousía does not enter the discourse as a definition but as a question to be answered: what is the primary, fundamental kind of being? What is prōtē ousíā?

While ousía means the same for both Plato and Aristotle as a question, they provide completely different answers to that question. Plato's answer is well known: the Form, which exists in a transcendent world of Forms, is prōtē ousíā, the primary, real being, of which the particular objects in the sensible world are just shadows. Against this Platonic background, Aristotle then provides his own answer in two works, Categories and Metaphysics, in which, notably, he provides different answers.

Categories, part 5 [6]

- Primary ousía is the individual, particular, concrete entity, of which species and accidents can be predicated without it being predicable of or attributable to anything else. This is actually stated in negative terms: “what is neither in a subject nor said of a subject”, i.e. the particular subject itself or "hypokeimenon" [7], literally “that which underlies or lies beneath” the universals (first of all species and genus) in which it falls and the accidents which inhere in it.

- Secondary ousía ("deutérā ousíā", pl. "deúterai ousíai") is the species (first of all) and the genus to which the particular subject belongs.

Metaphysics, book VII/Zeta [8]

- Primary ousía is the essence of the particular entity, which is its form, while the particular entity, the composite of form and matter, is ousía in a derivative sense. (The Aristotelian expression that the Latins translated as "essentia" is "to ti ên einai", "the what it was to be", although sometimes he uses the shorter expression "to ti esti", "the what it is".)

- Species and genus are not ousía.

A question arises at this point: Is for Aristotle the form of a particular entity a particular or a universal? This, in conjunction with his statement in Z.13 that no universal is ousía, is the most disputed issue regarding Aristotle's Metaphysics, and has given rise to a whole field of Aristotelian exegesis, in which the main lines are [9] [10]:

- Forms are not universal, and each particular entity has its own form which resides in that entity, so that all individuals of a given species have forms which are identical to one another but numerically different.

- Forms are universal, and Z.13 actually does not exclude them as ousía.

Since the second line is basically a reversion to Platonism, IMO it is extremely implausible that it may reflect Aristotle's personal position.

Summarizing the answers that Aristotle gives to the question "What is primary ousía?":

- Categories: the particular entity or "hypokeimenon", the subject which underlies all predicates and cannot be predicated of anything else.

- Metaphysics: the essence of the particular entity, which is its form, which may be understood in a particular or a universal sense.


2. Enter hypostasis, the original cognate of substantia

Etymologically [1] [2],

hypostasis = hypó ("under") + stásis ("a standing" = (hístēmi ("to stand") + -sis, verbal noun suffix)) = "that which stands under"

is a direct cognate of [3] [4] [5] [6]:

substantia = sub ("under") + stans ("standing", present active participle of stō ("stand")) = "that which stands under".

According to [7], the first recorded use of hypostasis as "substance" was in the book "On the cause of plants" by Aristotle's successor Theophrastus (c. 371 - c. 287 BC), while the term may have been introduced in the philosophical discourse either by the Stoic Poseidonius (c. 135 BC - c. 51 BC) according to some, or by the Epicurean Demetrius Lacon (fl. late 2nd century BC) according to others, in both cases with the meaning of objective or concrete existence or reality. Thus, real entities were said to "have hypostasis", whereas merely apparent or imaginary entities did not.

Recalling at this point that both the Stoic and the Epicurean philosophical schools were materialistic, the first conceiving the all-pervading Logos as a subtle fiery aether and the second conceiving reality as consisting just of atoms and void, it is clear that, to the extent that they used the term ousía, they would not have used it in the sense of form understood as universal or even in the sense of form at all, but in the sense of the individual, particular, concrete entity, the "hypokeimenon", “that which underlies or lies beneath”, which clearly overlaps with the meaning of hypostasis. Therefore, it is clear that for both Stoics and Epicureans the terms ousía and hypostasis were synonyms, but that was due to the specific sense in which both schools understood ousía.

Introducing now the Latins, who were now becoming interested in philosophy, into the picture:

Since, per linguistic design, substantia = hypostasis,

and, per Stoic and Epicurean understanding of ousía, hypostasis = ousía,

then, for the Latin-speaking Stoic- and Epicurean-dominated culture, substantia = ousía.

And that was the law of the philosophical land until the time of Plotinus.


3. Hebrews 1:3 in a Stoic and Epicurean lexical context.

The term "hypostasis" appears in the NT a total of 5 times: twice in the 2nd Letter to the Corinthians in the figurative sense of "confidence" in human beings, which either might lead to disappointment or is of a foolish kind to begin with (2 Cor 9:4; 11:17), twice in the Letter to the Hebrews in the figurative sense of "assurance" in God, which will never lead to disappointment (Heb 3:14; 11:1), and once in the Letter to the Hebrews in the proper sense:

"Who, being the radiance of his glory and the exact representation of his hypostasis," (Heb 1:3a).

In this passage, "Who" refers to the Son in verse 2, and "his" refers to "ho Theos" in verse 1, an expression which in the NT, when used without further qualification, refers to God the Father. The Greek original of "the exact representation of his hypostasis" is "charaktēr tēs hypostaseōs autou".

In order to understand correctly Heb 1:3, we must first take into account the lexical context of the human author at the time of writing it. As is well known, the Letter to the Hebrews was written before the destruction of the Second Temple in 70 AD, since it consistently refers to the sacrificial system of the Mosaic Law as still ongoing (Heb 8:4-5; 9:7-10,13,25; 10:1-2; 13:11). On the other hand, it was probably written shortly before 70 AD, since the exhortation to "Remember your leaders, those who spoke to you the word of God. Consider the outcome of their way of life, and imitate their faith." (Heb 13:7) seems to refer either to James, brother of the Lord, killed in Jerusalem in 62 AD, or to Peter and Paul, killed in Rome in 64 and 67 AD. Therefore, the Letter was written in a cultural context in which, for the last 150 years, the prevalent philosophical schools had been Stoicism and Epicureanism, both of which, as we saw in the previous section, used the term hypostasis with the meaning of objective or concrete existence or reality.

Then we must note that the very notion of "charaktēr" - impressed image or copy of something, reproduction, representation [1] - necessarily implies a numerical distinction between the original and its charaktēr. Therefore, stating that the Son is "the charaktēr of the Father's hypostasis" necessarily implies that the Son is or has a numerically different hypostasis from that of the Father, irrespective of what hypostasis may mean in that context.

Taking these two points in conjunction, Heb 1:3 is saying that the Son is the exact representation of the objective, concrete reality of the Father. Therefore, the objective, concrete reality of the Son is numerically different from that of the Father.

Once we understand Heb 1:3 this way, we must answer two questions:

3.1. Is Heb 1:3 consistent with trinitarian orthodoxy, Arianism, tritheism, or all of them?

The key to answer this question is to realize that, in orthodox trinitarian doctrine, the divine nature does not exist in reality separate from the divine Persons. I.e. the common divine nature, abstracted from and without the personal properties, does not have objective, concrete reality. (And thus, in the philosophical lexicon of 1st century AD, it does not "have hypostasis".) It is the Father, the Son and the Holy Spirit Who have objective, concrete reality. (And thus, in the philosophical lexicon of 1st century AD, "have hypostasis".) And since the Father is really not the Son, the objective, concrete reality of the Son (-his hypostasis in the philosophical lexicon of 1st century AD-) is numerically different from that of the Father, which is precisely the sense of Heb 1:3, as we saw above. Therefore, Heb 1:3 is consistent with trinitarian orthodoxy.

Note that if in the framework of trinitarian orthodoxy we want to use the term hypostasis in a sense consistent with Heb 1:3, we must use it in the post-Cappadocian sense, because, as we saw above, Heb 1:3 necessarily implies that the Son is or has a numerically different hypostasis from that of the Father, irrespective of what hypostasis may mean.

Clearly Heb 1:3 is also consistent with Arianism and tritheism, which also posit that the objective, concrete reality of the Son is numerically different from that of the Father. The only inconsistency of Heb 1:3 is with modalism.

3.2. What is the correct translation of hypostasis in Heb 1:3?

As we will see, the choice of Latin-derived words for "his hypostasis" to convey the original sense of "the objective, concrete reality of the Father" can no longer, after the trinitarian debates of the IV century and the settlement of the theological lexicon, be made independently from the adoption of a particular theological position. This is because, as we saw above, Heb 1:3 necessarily implies that the Son is or has a numerically different hypostasis from that of the Father, irrespective of what hypostasis may mean. With this "charaktēr corollary" in mind, let's examine the options for translating hypostasis.

a. Substance. While "substantia" in the 1st century AD was etymologically and semantically equivalent to "hypostasis", after Tertullian coined the formula "tres Personae, una Substantia" early in the III century, substantia came to mean, among Latin-speaking Christians, the single infinite spirit that the Father, the Son and the Holy Spirit have in common. This meaning of substantia as equivalent to ousía in the Nicene sense was reinforced by that Council establishing that hypostasis, the cognate and original equivalent of substantia, was to be understood as synonym of ousía. Therefore, translating hypostasis in Heb 1:3 as "substance" after Nicaea has as a consequence, per the "charaktēr corollary" recalled above, that the translated text necessarily implies that the Son has a numerically different substance, i.e. ousía in the Nicene sense, from that of the Father, which amounts to stating Arianism if the substances are qualitatively different or tritheism if they are qualitatively identical.

In other words, translating hypostasis as substance would be perfect if we were translating Heb 1:3 into 1st century Latin, but after the Tertullian-initiated and Nicaea-confirmed understanding of substantia as ousía in the Nicene sense, it causes the passage to state either Arianism or tritheism.

b. Being. This term is ambiguous, and in principle could convey the original sense of "objective, concrete reality" as either post-Nicaean notion, ousía or Person, though it sounds more like the former, with which it is etymologically related. Therefore, it is in principle compatible with all theological positions, though it sounds more as Arian or tritheistic.

c. Person. This term is fully consistent with trinitarian orthodoxy (and also with the other theological positions, since it says nothing about whether the Father and the Son have the same ousía.) It has two drawbacks: first, it has no etymological relation with hypostasis, and second, it is not a general equivalent to hypostasis but only to a hypostasis of a personal nature.

d. Subsistence. This term was invented around 400 by Tyrannius Rufinus (344-411) to convey the post-Cappadocian meaning of hypostasis, for which the term substantia was no longer available since its meaning had been settled in Nicaea as the Latin equivalent of ousía [2] [3]. It was built by taking substantia and replacing the derivative of the verb stō by the derivative of the cognate and synonym verb sistō [4] [5]:

substantia = sub ("under") + stans ("standing", present active participle of stō ("stand")) = "that which stands under".

subsistentia = sub ("under") + sistēns ("standing", present active participle of sistō ("stand")) = "that which stands under".

Therefore translating hypostasis as subsistence is etymologically perfect, generally valid, and fully consistent with trinitarian orthodoxy (and also with the other theological positions, just as the case of person). The drawback is that the word has a completely unrelated usual meaning in English.


4. Trinitarian orthodoxy and the three possible ways to fall from it.

I will state trinitarian orthodoxy by using exclusively statements in the NT or readily inferred from its text, without using the formulas in the Pseudo-Athanasian Creed or Quicumque Symbol, because using a creed composed in the V century (and not by S. Athanasius but in southern Gaul) would not be appropriate for this historically-focused work.

To note, even when for simplicity I will consider only the Father and the Son, I will always speak about "trinitarian" orthodoxy, doctrine, etc.

Trinitarian orthodoxy can be formulated on the basis of 3 sets of NT statements, each consisting of one primary and several supporting statements:

1. 'yet for us there is one God, the Father,' (1 Cor 8:6a)

"This is eternal life, that they may know You, the only true God," (Jn 17:3a)

Jesus answered, "The foremost [commandment] is, 'Hear this O Israel: The Lord our God, the Lord is one,'" (Mk 12:29)

[Here Jesus quoted the Shema: 'Shema Yisrael, YHWH eloheinu, YHWH echad.' (Deut 6:4).]

2. "I and the Father are one." (Jn 10:30)

[If Jesus was speaking in Hebrew, He probably said "Ani veha'av echad", ending with echad as in the Shema.]

In the beginning was the Word, and the Word was with God, and the Word was God. (Jn 1:1)

whose are the fathers, and from whom is the Christ according to the flesh, Who is God over all, blessed forever. Amen. (Rom 9:5)

Who, existing in the form of God, did not consider to be equal with God something to be grasped, (Phil 2:6)

No one has ever seen God. The only begotten God, the One who Is in the bosom of the Father, He has made Him known. (Jn 1:18)

Plus 5 passages where the Son is referred as "ho Theos" with a qualification: Mt 1:23; Jn 20:28; Tit 2:13; 2 Pet 1:1; 1 Jn 5:20.

3. The Son and the Father are really distinct personal subjects.

[While the above is not an NT statement, it is an unavoidable straightforward conclusion from many NT statements, such as:]

"You are My Son, the beloved; in You I am well pleased." (Mk 1:11b)

"For the Father loves the Son and shows Him all things that He does." (Jn 5:20a)

"As the Father knows Me, I also know the Father; and I lay down My life for the sheep." (Jn 10:15)

"But that the world may know that I love the Father, and as the Father has commanded Me, thus I do." (Jn 14:31)

"Now, Father, glorify Me together with Yourself, with the glory which I had with You before the world was." (Jn 17:5)


Correspondingly, there are 3 possible ways to fall from trinitarian orthodoxy, each by denying one of the statements:

- Denial that there is one God = tritheism
- Denial that the Son and the Father are one = Arianism
- Denial that the Son and the Father are really distinct = modalism or Sabellianism

Of those ways to fall, the first to occur historically was modalism (Sabellius fl. ca. 215), but it was Arianism which presented the biggest threat to orthodoxy and prompted the Church to elaborate a precise formulation of trinitarian doctrine. Tritheism, in turn, was never a significant threat but just a potential accusation by the enemies of orthodoxy from within and without, for which no room should be left.


5. The "one ousía" answer to Arianism, its modalistic and tritheistic risks, and Nicaea's "one hypostasis" as prevention of the second.

Since Arians denied that the Son and the Father were one, they had to interpret Jesus' words "I and the Father are one." (Jn 10:30) in the sense of only moral oneness and not ontological oneness. To counter that eisegesis, the orthodox sought for the right word to add to Jn 10:30 to convey unequivocally the sense of ontological oneness: "I and the Father are one"... what?

We arrive at the same question from four key statements by Jesus of his divinity that were not mentioned in the previous section: the 4 times in which He explicitely applied to Himself the divine Name in the first person revealed in Ex 3:14: "Ehyeh", "Ego Eimí", I Am": Jn 8:24,28,58 & 13:19. If each of the Father and the Son names Himself "Ego Eimí", "I Am", then Each is a distinct "I" but Both are the same... what?

The natural answer to that question was the term ousía, which derived precisely from the verb "eimí", "to be". So, the initial orthodox answer to the Arian challenge was: the Father and the Son are one ousía and two prósōpa, one being and two persons. Now, each term in that answer, ousía and prósōpon, was at risk of misinterpretation resulting in another heresy.

The risk of misinterpretation of ousía came from the fact that the philosophical stage at the beginning of the IV century was very different from that of around 70 AD when the Letter to the Hebrews was written. Platonism had come back with Plotinus (204-270) and Porphyry (234-305), and with it the notions of forms and universals and therefore the issue of the exact meaning of ousía. Let us recall from section 1 that ousía had entered the philosophical discourse, some 700 years before Nicaea, not as a definition but as a question to be answered, and for which Aristotle had provided two different answers, one in the Categories and another in the Metaphysics, the second of which could in turn be interpreted in two different ways:

C: the individual, particular, concrete subject or "hypokeimenon", “that which underlies or lies beneath”;
M1: the essence or form, understood as particular;
M2: the essence or form, understood as universal.

Each of these senses of ousía led to a different sense of the statement that the Father and the Son were "homoousious", "of the same ousía":

C: They were the same particular, concrete subject.
M1: They had the same essence or form, understood as particular.
M2: They had the same essence or form, understood as universal.

It is easy to see that, while sense C amounts to modalism, sense M2 amounts to tritheism, since the case would be the same as stating that three horses have the same essence or form. It was probably to prevent the risk of understanding ousía as a universal of which there were multiple instances, or equivalently, of understanding the expression "of the same ousía" in the sense of only qualitative identity instead of numerical identity, that the Nicaea fathers added hypostasis - which, as we saw in section 2, had the meaning of objective or concrete existence or reality - as synonym of ousía, anathematizing those who asserted that the Son of God "is of another hypostasis or ousía" [1] [2]. Since substantia was originally the cognate and equivalent of hypostasis, making hypostasis equivalent to ousía (M1) reinforced the Western understanding of substantia as the Latin equivalent of ousía (M1) that had begun with Tertullian.

Whereas the addition of hypostasis as synonym of ousía effectively prevented the M2 sense of ousía as universal, which leads to tritheism, it in effect promoted the C sense - which is evident from the etymological equivalence of hypostasis, literally "that which stands under", with hypokeimenon - which leads to modalism.

Which takes us precisely to the risk of misinterpretation of prósōpon, which came from the fact that it meant "face", "mask" or "character in a theatrical play" [3]. Thus modalists could claim that they were in complete agreement with the definition of Nicaea.


6. The three Hypostases formula: appearance, toleration by St. Athanasius, resistance by St. Jerome, and my argument for it.

As noted in section 3, the use of hypostasis as synonym of ousía, so that the Father and the Son were said to be "of the same hypostasis", was inconsistent with the sense of hypostasis in Heb 1:3, since that passage necessarily implies - from the very notion of "charaktēr" as impressed image or copy, reproduction, representation - that the Son is or has a numerically different hypostasis from that of the Father, irrespective of what hypostasis may mean.

It was not this consideration, however, what motivated orthodox theologians to advocate formulating trinitarian doctrine in terms of three hypostases, but the realization that using all the terms that can convey a sense of objective reality - i.e. hypostasis and ousía - to denote the common being of the Father and the Son amounted to leaving the door open for modalists to claim that they were in full agreement with the dogmatic definitions of the Church.

The notion of three Hypostases had been introduced in Christian theology by Origen and had been used also by his former student St. Dionysius of Alexandria. Its first documented use after Nicaea was by (also Alexandrian) St. Athanasius, in his work "In Illud Omnia", written probably c. 335 [1] [2]:

"For the fact of those venerable living creatures [Isa 6:3; Rev 4:8] offering their praises three times, saying 'Holy, Holy, Holy,' proves that the three Hypostases are perfect, just as in saying 'Lord,' they declare the one Ousía."

After that, the expression was not used again by St. Athanasius, in deference to the anathema of Nicaea [1], but was used by non-Nicene bishops, e.g. in the Dedication creed of the council of Antioch of 341 and in a letter by the homoiousian bishop George of Laodicea in 359. But by the time of the Council of Alexandria of 362, presided by St. Athanasius, the expression was already being used by people holding homoousian orthodoxy, as attested by the letter to the Church in Antioch written by that Council, known as "Tomus ad Antiochenos" [3] [4], which acknowledged that both expressions, "three hypostases" and "one hypostasis", could used in a sense consistent with homoousian orthodoxy.

It is illustrative to read the passages in the Antiochene Tome that report the reasons stated by the parties using each expression for their doing so:

The Antiochene Tome, on the Antiochian party that spoke of three Hypostases

For as to those whom some were blaming for speaking of three Hypostases, on the ground that the phrase is unscriptural and therefore suspicious, we thought it right indeed to require nothing beyond the confession of Nicaea, but on account of the contention we made enquiry of them, whether they meant, like the Arian madmen, hypostases foreign and strange, and alien in ousía from one another, and that each hypostasis was divided apart by itself, as is the case with creatures in general and in particular with those begotten of men, or like different substances, such as gold, silver, or brass — or whether, like other heretics, they meant three Beginnings and three Gods, by speaking of three Hypostases.

They assured us in reply that they neither meant this nor had ever held it. But upon our asking them 'what then do you mean by it, or why do you use such expressions?' they replied, Because they believed in a Holy Trinity, not a trinity in name only, but existing and subsisting in truth, 'both a Father truly existing and subsisting, and a Son truly substantial and subsisting, and a Holy Spirit subsisting and really existing do we acknowledge,' and that neither had they said there were three Gods or three beginnings, nor would they at all tolerate such as said or held so, but that they acknowledged a Holy Trinity but One Godhead, and one Beginning, and that the Son is homoousios with the Father, as the fathers said;

The Antiochene Tome, on the Antiochian party that spoke of one Hypostasis

Having accepted then these men's interpretation and defense of their language, we made enquiry of those blamed by them for speaking of one Hypostasis, whether they use the expression in the sense of Sabellius, to the negation of the Son and the Holy Spirit, or as though the Son were non-substantial, or the Holy Spirit impersonal. But they in their turn assured us that they neither meant this nor had ever held it, but 'we use the word Hypostasis thinking it the same thing to say Hypostasis or Ousía;' 'But we hold that there is one, because the Son is of the Ousía of the Father, and because of the identity of nature [physeos]. For we believe that there is one Godhead, and that it has one nature [physis], and not that there is one nature of the Father, from which that of the Son and of the Holy Spirit are distinct.'

End of quotes from the Antiochene Tome.

Note that the party speaking of one hypostasis mentioned the term "physis", "nature". Unlike ousía, physis is used in the NT, in a well-known passage that speaks of "the" divine nature (2 Pet 1:4), implying that there is one divine nature common to the Father, the Son and the Holy Spirit.

In stark contrast with St. Athanasius in the Council of Alexandria of 362, St. Jerome, in his epistle 15 to Pope St. Damasus, written in 376 or 377 [5] [6] [7], manifests his deep trouble with the use of the formula "three hypostases":

St. Jerome, in his epistle 15 to Pope St. Damasus of 376 or 377

3. Just now, I am sorry to say, those Arians, the Campenses, are trying to extort from me, a Roman Christian, their unheard-of formula of three hypostases. And this, too, after the definition of Nicaea and the decree of Alexandria, in which the West has joined. Where, I should like to know, are the apostles of these doctrines? Where is their Paul, their new doctor of the Gentiles? I ask them what three hypostases are supposed to mean. They reply three persons subsisting. I rejoin that this is my belief. They are not satisfied with the meaning, they demand the term. Surely some secret venom lurks in the words. "If any man refuse," I cry, "to acknowledge three hypostases in the sense of three things hypostatized, that is three persons subsisting, let him be anathema." Yet, because I do not learn their words, I am counted a heretic. "But, if any one, understanding by hypostasis ousía ["usian"], deny that in the three persons there is one hypostasis, he has no part in Christ." Because this is my confession I, like you, am branded with the stigma of Sabellianism.

4. If you think fit enact a decree; and then I shall not hesitate to speak of three hypostases. Order a new creed to supersede the Nicene; and then, whether we are Arians or orthodox, one confession will do for us all. In the whole range of secular learning hypostasis never means anything but ousía ["usian"]. And can any one, I ask, be so profane as to speak of three substances? There is one nature of God and one only; and this, and this alone, truly is. For that which subsists by itself, it does not have any other source, but it is his own. All other things, which are created, although they appear to be, are not. For there was a time when they were not, and that which once was not may again cease to be. God alone who is eternal, that is, who has no beginning, truly has name of essence. Therefore also He says to Moses from the bush, "I am who I am," and Moses says of Him, "He who is, sent me." [Ex 3:14] Certainly at that time the angels, the sky, the earth, the sea all existed: and how the common name of essence God claimed as properly his own? But because that nature alone is perfect, and in the three persons the one Deity subsists, which truly is, and is one nature; whosoever in the name of religion declares that there are three, that is three hypostases, that is ousíai ["usias"], is striving really to predicate three natures of God. And if this is true, why are we severed by walls from Arius, when in dishonesty we are one with him?

End of quote from St. Jerome.

Thus, the reason why an Antiochian party was using the formula "one hypostasis" in 362, as they explained it to St. Athanasius, and the reason why St. Jerome was rejecting the formula "three hypostases" in 376-377, as he explained it to St. Damasus, was exactly the same: for them, hypostasis meant the same as ousía. Which was just inaccurate, because as we saw in section 1 and summarized in section 5 - and will repeat here due to its importance, at the risk of tiring readers - ousía had entered the philosophical discourse not as a definition but as a question to be answered, and for which Aristotle had provided two different answers, one in the Categories and another in the Metaphysics, the second of which could in turn be interpreted in two different ways:

C: the individual, particular, concrete subject or "hypokeimenon", “that which underlies or lies beneath”;
M1: the essence or form, understood as particular;
M2: the essence or form, understood as universal.

Hypostasis, in turn, means "objective, concrete reality", and is thus equivalent to only one of the three possible senses of ousía, the C: the individual, particular, concrete subject or "hypokeimenon".

It would seem that in the case of entities of a spiritual nature there is no real difference between the C and M1 interpretations of ousía, as these entities are pure forms without matter. And this is certainly the case of created spiritual beings, i.e. angels. But it is definitely not the case of the divine nature, because each of the three divine Persons is numerically the same divine essence or form as the other Persons, and yet each Person is a really distinct subject.

Thus, the Trinity posed a unique, unprecedented challenge to ontology:

- while in the case of all created entities there is a one-to-one correspondence between a particular subject and its essence or form, understood as particular,
- in the case of the Deity there are three really, objectively distinct subjects Who are numerically the same divine essence or form.

Therefore, when we speak of the numerically one divine ousía we are using ousía in sense M1, which is not the sense equivalent to hypostasis. Hypostasis, instead, is an appropriate term for referring to each of the three really, objectively distinct divine Persons. This, in conjunction with the statement in Heb 1:3 that the Son is "the charaktēr - impressed image or copy, reproduction, representation - of the Father's hypostasis", which necessarily implies that the Son is or has a numerically different hypostasis from that of the Father, provides an extremely strong basis for using hypostasis as synonym of divine Person.

Excursus: A last-ditch attempt by "one hypostasis" advocate 1H, in dialogue with "three hypostases" advocate 3H.

1H: Wait! If "hypokeimenon" is "the subject which underlies all predicates", wouldn't that be the one divine ousía?

3H: Certainly not according to the Lord Jesus or the Apostle John, as their statements of divine attributes have "ho Theos", i.e. God the Father, as subject of the copulative statement. Thus:

"No one is good, except God alone." in Mk 10:18 and Lk 18:19 is "Oudeis agathos, ei mē heis, ho Theos."

"God is Spirit" in Jn 4:24 is "Pneuma ho Theos" (in reverse order just as the last clause in Jn 1:1).

"God is light" in 1 Jn 1:5 is "ho Theos phōs estin".

"God is love" in 1 Jn 4:8,16 is "ho Theos agapē estin".

1H (puzzled): And how is that consistent with consubstantiality?

3H: Because the Son is all that God the Father is, in a numerical identity sense, except Father. So whatever is predicated of God the Father, except being Father, is also predicated of the Son.

End of excursus.

But it took time and effort in the IV century for orthodox theologians to get to see this clearly, and the first decisive steps in this direction were made by St. Basil of Caesarea and his brother St. Gregory of Nyssa.


7. The three Hypostases formula: proposal by St. Basil and St. Gregory of Nyssa and increasingly official Church adoption since 382.

After Nicaea, the first orthodox theologian to propose a notion of hypostasis distinct from that of ousía in a published work was St. Basil of Caesarea (330-379), and he does it in his epistles 214 (375) to Count Terentius [1] and 236 (376) to Amphilochius [2]. In both letters, the main motive for using hypostasis as synonym of Person is that, if the orthodox keep speaking of one hypostasis, they set the stage for the Arians to accuse them of Sabellianism (modalism).

St. Basil, in his epistle 214 (375) to Count Terentius

3. Consider well, my excellent friend, that the falsifiers of the truth, who have introduced the Arian schism as an innovation on the sound faith of the Fathers, advance no other reason for refusing to accept the pious opinion of the Fathers than the meaning of the homoousion which they hold in their wickedness, and to the slander of the whole faith, alleging our contention to be that the Son is consubstantial in hypostasis. If we give them any opportunity by our being carried away by men who propound these sentiments and their like, rather from simplicity than from malevolence, there is nothing to prevent our giving them an unanswerable ground of argument against ourselves and confirming the heresy of those whose one end is in all their utterances about the Church, not so much to establish their own position as to calumniate mine. What more serious calumny could there be? What better calculated to disturb the faith of the majority than that some of us could be shewn to assert that there is one hypostasis of Father, Son, and Holy Ghost? We distinctly lay down that there is a difference of Persons; but this statement was anticipated by Sabellius, who affirms that God is one by hypostasis, but is described by Scripture in different Persons, according to the requirements of each individual case; sometimes under the name of Father, when there is occasion for this Person; sometimes under the name of Son when there is a descent to human interests or any of the operations of the oeconomy; and sometimes under the Person of Spirit when the occasion demands such phraseology. If, then, any among us are shewn to assert that Father, Son and Holy Ghost are one in subject ["hypokeimenon"], while we maintain the three perfect Persons, how shall we escape giving clear and incontrovertible proof of the truth of what is being asserted about us?

4. The non-identity of hypostasis and ousia is, I take it, suggested even by our western brethren, where, from a suspicion of the inadequacy of their own language, they have given the word ousia in the Greek, to the end that any possible difference of meaning might be preserved in the clear and unconfounded distinction of terms. If you ask me to state shortly my own view, I shall state that ousia has the same relation to hypostasis as the common has to the particular [a]. Every one of us both shares in existence by the common term of essence (ousia) and by his own properties is such an one and such an one. In the same manner, in the matter in question, the term ousia is common, like goodness, or Godhead, or any similar attribute; while hypostasis is contemplated in the special property of Fatherhood, Sonship, or the power to sanctify [b]. If then they describe the Persons as being without hypostasis, the statement is per se absurd; but if they concede that the Persons exist in real hypostasis, as they acknowledge, let them so reckon them that the principle of the homoousion may be preserved in the unity of the Godhead, and that the doctrine preached may be the recognition of true religion, of Father, Son, and Holy Ghost, in the perfect and complete hypostasis of each of the Persons named.

St. Basil, in his epistle 236 (376) to Amphilochius

6. The distinction between ousia and hypostasis is the same as that between the general and the particular [a]; as, for instance, between the animal and the particular man. Wherefore, in the case of the Godhead, we confess one essence or substance so as not to give a variant definition of existence, but we confess a particular hypostasis, in order that our conception of Father, Son and Holy Spirit may be without confusion and clear. If we have no distinct perception of the separate characteristics, namely, fatherhood, sonship, and sanctification [b], but form our conception of God from the general idea of existence, we cannot possibly give a sound account of our faith. We must, therefore, confess the faith by adding the particular to the common. The Godhead is common; the fatherhood particular. We must therefore combine the two and say, "I believe in God the Father." The like course must be pursued in the confession of the Son; we must combine the particular with the common and say "I believe in God the Son," so in the case of the Holy Ghost we must make our utterance conform to the appellation and say "in God the Holy Ghost." Hence it results that there is a satisfactory preservation of the unity by the confession of the one Godhead, while in the distinction of the individual properties regarded in each there is the confession of the peculiar properties of the Persons. On the other hand those who identify essence or substance and hypostasis are compelled to confess only three Persons ["Prosopa"], and, in their hesitation to speak of three hypostases, are convicted of failure to avoid the error of Sabellius, for even Sabellius himself, who in many places confuses the conception, yet, by asserting that the same hypostasis changed its form to meet the needs of the moment, does endeavour to distinguish persons.

End of quotes from St. Basil.

[a] The statement that the relation of ousía to hypostasis is the same as that of the common to the particular is ambiguous, because the relation of hypostasis to ousía is not the same in the divine Persons as in created entities. We will come back to this point later. Let us say now that, while ousía can be understood as universal (M2) in the case of created entities, it cannot be understood that way in the case of the Deity, because that amounts to tritheism.

[b] St. Basil had not yet come to understand that the personal property of the Holy Spirit was passive spiration or procession, i.e. that the Holy Spirit was breathed eternally by the Father and the Son as their mutual love, irrespective of whether They would create a universe or not.

St. Gregory of Nyssa (335-394) devotes his epistle 35 (c. 380) addressed to his brother Peter - which is often referred to as St. Basil's epistle 38 to his brother Gregory - to the difference between ousía and hypostasis. St. Gregory starts by distinguishing between the common or general and the particular, and provides a definition of hypostasis [3].

St. Gregory of Nissa, in his epistle 35 (c. 380) to his own brother Peter

1. Since many fail to distinguish in the mystic dogmas the ousía, which is common, from the principle of the hypostases, they fall into ambivalent notions and think that it makes no difference at all whether they say "ousía" or "hypostasis". Consequently some who accept such notions uncritically are happy to speak of "one hypostasis" in the same breath as "one ousía", while others who accept three hypostases think that they are bound by this confession to assert an equal number of ousíai. For this reason, so that you too may not succumb to similar notions, I have put together a short treatise for you as a memorandum on this topic. Now the meaning of the expressions, to put it briefly, is as follows:

2. In the whole class of nouns, expressions used for things which are plural and numerically diverse have a more general sense, as for example "man". For anyone who employs this noun indicates the common nature, not limiting it to any particular man known by such a term. For "man" has no more reference to Peter than it has to Andrew, John, or James. The commonality of what is signified extends alike to all ranked under the same name and requires some further distinction if we are to understand not "man" in general, but Peter or John.

[...]

3. This then is what we affirm: what is spoken of individually is indicated by the expression "hypostasis". For when someone says "a man", it strikes upon the ear as a somewhat diffuse concept due to the indefiniteness of its meaning. Though the nature is indicated, that thing which subsists and is indicated by the noun individually is not made clear. But if someone says "Paul", he shows the nature as subsisting in that which is indicated by the noun.

This therefore is the "hypo-stasis": not the indefinite notion of the ousía, which finds no "standing" ["stasis"] because of the commonality of what is signified, but that conception which, through the manifest individualities ["idiomata"], gives standing and circumscription in a particular thing to the common and uncircumscribed.

[...]

Transpose, then, to the divine dogmas the same principle of differentiation which you acknowledge with regard to ousía and hypostasis in our affairs, and you will not go wrong.

End of quote from St. Gregory of Nyssa.

Down in section 6 of the same letter, St. Gregory says:

"But perhaps someone may think that the account given here of the hypostasis does not tally with the conception in the apostle's writing where he says of the Lord that "He is the brightness of his glory and the charaktēr of his hypostasis" [Heb 1:3]."

After explaining where the apparent conflict resides, St. Gregory devotes section 6 trying to solve it. Here I argue that the passage poses no conflict at all with his account of the hypostasis.

The starting point is that, just as the hypostasis of the Father is characterized by fontal plenitude and paternity (i.e. in a Bonaventuran framework, in which unbegottenness or innascibility is understood in a positive sense of fontal plenitude, which implies paternity), so the hypostasis of the Son is characterized by being the impress of the hypostasis of the Father (Heb 1:3), or in Johannine terms, by being generated by the Father when He enunciates, in eternity, his perfect knowledge of Himself, which is why the Son is called the Word (Jn 1:1).

Thus, given that being the impress of God Unbegotten implies being God Only Begotten ("Monogenes Theos" in Jn 1:18), and not being also Unbegotten, Heb 1:3 does not pose any conflict, real or apparent, to the notion of hypostasis as the only divine ousía instantiated according to the corresponding idiomaton or personal property.

In 381, i.e. around one year after Gregory's letter to Peter, the second Ecumenical Council convened in Constantinople, and the next year, i.e 382, a synod of bishops assembled in that city and sent a Synodical Letter to Pope Damasus and other Western bishops, which is the first official (though not ecumenical) Church document speaking of three Hypostases [4]:

Letter from the Constantinople Synod of 382 to Pope Damasus

What we have undergone — persecutions, afflictions, imperial threats, cruelty from officials, and whatever other trial at the hands of heretics — we have put up with for the sake of the gospel faith established by the 318 fathers at Nicaea in Bithynia. You, we and all who are not bent on subverting the word of the true faith should give this creed our approval. It is the most ancient and is consistent with our baptism. It tells us how to believe in the name of the Father and of the Son and of the Holy Spirit: believing also, of course, that the Father, the Son and the Holy Spirit have a single Godhead and power and substance, a dignity deserving the same honour and a co-eternal sovereignty, in three most perfect Hypostases, or three perfect Persons. So there is no place for Sabellius’s diseased theory in which the hypostases are confused and thus their proper characteristics destroyed.

End of quote from the Constantinople Synod of 382.

In 431 the third Ecumenical Council convened in Ephesus. The third letter of St. Cyril of Alexandria to Nestorius, which was read at the council and included in the proceedings, spoke of the Hypostases of the Word and of the Holy Spirit [5]:

St. Cyril of Alexandria, in his 3rd letter to Nestorius

All the expressions, therefore, that occur in the gospels are to be referred to one Person, the one enfleshed Hypostasis of the Word.

For even though the Spirit exists in his own Hypostasis and is thought of on his own, as being Spirit and not as Son, even so He is not alien to the Son.

End of quote from St. Cyril.

In 451 the fourth Ecumenical Council convened in Chalcedon and proclaimed a Christological definition which contains all the terms considered so far: ousía, prosopon, hypostasis, and nature [6] [7]:

Definition of the Ecumenical Council of Chalcedon

Following, therefore, the holy fathers, we all with one voice teach the confession of one and the same Son, our Lord Jesus Christ:
the Same perfect in Godhead, the Same perfect in manhood,
truly God and the Same truly man, of a rational soul and body;
consubstantial ["homoousios"] with the Father as regards the Godhead,
and the Same consubstantial ["homoousios"] with us as regards the manhood,
like us in all things apart from sin,
before the ages begotten from the Father as regards the Godhead,
and in the last days the Same, for us and for our salvation, [born] from Mary, the Virgin Theotokos, as regards the manhood,
one and the same Christ, Son, Lord, Only-begotten,
acknowledged in two natures without confusion, without change, without division, without separation,
- the difference of the natures being in no way destroyed by the union,
but rather the distinctive character of each nature being preserved
and coming together into one Person ["Prosopon"] and one Hypostasis -
not parted or divided into two persons ["Prosopa"],
but one and the same Son, Only-begotten God, Logos, Lord Jesus Christ.

End of quote from the Council of Chalcedon.

Finally, in 553 the fifth Ecumenical Council convened in Constantinople and proclaimed a series of trinitarian and Christological definitions, the first of which explicitely identifies ousía with physis and hypostasis with prosopon [7]:

First Anathema of the Constantinople II Ecumenical Council

If anyone does not confess that the physis or ousía of the Father, of the Son, and of the Holy Spirit is one, as also the power and the authority; [if anyone does not confess] a consubstantial ["homoousios"] Trinity, one Godhead worshipped in three Hypostases or Persons: let him be anathema. For there is one God and Father from Whom are all things; and one Lord Jesus Christ through Whom are all things; and one Holy Spirit in Whom are all things.

End of quote of the Constantinople II Ecumenical Council.


8. Post-Chalcedon problem A: ambiguity in ousía or in homoousios.

The issue addressed in this section is not a problem at all at the theological level (in contrast with the issue addressed in the next section), but basically a matter of semantics. I find it worthwhile, however, since it provides closure to the question with which we opened the article.

Recalling (for the last time!) that ousía had entered the philosophical discourse as a question to be answered, and for which Aristotle had provided two different answers, one in the Categories and another in the Metaphysics, the second of which could in turn be interpreted in two different ways:

C: the individual, particular, concrete subject or "hypokeimenon", “that which underlies or lies beneath”;
M1: the essence or form, understood as particular;
M2: the essence or form, understood as universal.

it is clear that, after the proposal on philosophical terminology by St. Basil and St. Gregory of Nyssa was accepted by the Church, C was no longer one of the possible meanings of ousía, but became associated exclusively with hypostasis.

But after Chalcedon, the question of whether the sense of ousía was M1 or M2 was still open, as can be seen in the definition by Chalcedon that the Incarnated Logos is "homoousios with the Father as regards the divinity" and "homoousios with us as regards the humanity".

Given that "homoousios" means "of the same ousía", and that:

- whereas the Father and the Son are numerically the same one and only divine Ousía,
- Jesus and each of us are numerically distinct instances of the human ousía,

the statement of the double consubstantiality of the Incarnated Logos implies either that (solution 1):

- ousía is meant univocally, in a particular sense (M1) for both the divine Persons and created entities, and
- "same ousía" is meant ambiguously, in a numerical identity sense for the divine Persons and in a qualitative identity sense for created entities;

or that (solution 2):

- ousía is meant ambiguously, in a particular sense (M1) for the divine Persons and in a universal sense (M2) for created entities, and
- "same ousía" is meant univocally, in a numerical identity sense for both the divine Persons and created entities.

Since using ousía in a universal sense is Platonism, my personal solution is 1. In this case, if we wanted to avoid the ambiguity in "homoousios", we would have to reserve "homoousios", "consubstantial" for numerical identity and use "isoousios", "equisubstantial" for qualitative identity, so that the definition would state "consubstantial [homoousios] with the Father as regards the divinity" and "equisubstantial [isooousios] with us as regards the humanity".

Now, what is the Church's solution for this problem? For the Roman Catholic Church, we can find out from the definition by the Ecumenical Council of Trent, session 13, that "by the consecration of the bread [...], a conversion is made of the whole substance of the bread into the substance of the body of Christ our Lord," as clearly in both cases "substance" is meant in a particular sense.


9. Post-Chalcedon problem B: why is it that Jesus' objective, concrete, really existing human nature is not a hypostasis?

Strictly speaking, this problem is Post-Ephesus, since that Council had already defined the doctrine of the one hypostasis of Christ, although in a way less explicit than that of Chalcedon. Quoting from the Third letter of Cyril to Nestorius, read at the council of Ephesus and included in its proceedings [1] [2]:

St. Cyril of Alexandria, in his Third letter to Nestorius

For we do not divide up the words of our Saviour in the gospels among two hypostases or persons.

All the expressions, therefore, that occur in the gospels are to be referred to one person, the one enfleshed hypostasis of the Word. For there is one Lord Jesus Christ, according to the scriptures.

II. If anyone does not confess that the Logos Who is from God the Father has been united to flesh according to hypostasis, [...] let him be anathema.

IV. If anyone distributes between two persons or hypostases the expressions used either in the gospels or in the apostolic writings, whether they have been said by the holy writers of Christ, or by Him of Himself, [...] let him be anathema.

End of quote of St. Cyril.

The question of why Jesus' human nature is not a hypostasis could be just left as a theological mystery, as in fact Cyril did in his Second letter to Nestorius, also read at the council of Ephesus and included in its proceedings [2]:

"the Logos became man by uniting to Himself according to Hypostasis, in an ineffable and incomprehensible manner, flesh ensouled with rational soul."

Still, it is wholly legitimate to try to understand [3] how the two natures subsist in one hypostasis. As detailed by Pavouris (2001) [2], the first steps to such an understanding were made by John of Caesarea aka John the Grammarian (fl 510-520) and by Leontius of Jerusalem (fl. probably between 538-550). Quoting from [2]:

Pavouris (2001) [2], on John the Grammarian

the Grammarian teaches that the union in Christ was effected 'according to synthesis'. [...] This union 'according to synthesis' is also called 'enhypostatic'. This christology of the 'enhypostaton' is the major contribution of the neo-Chalcedonians to christological doctrine. The primary meaning of the term is 'union of two or more ousiai in one hypostasis'. Yet, like Leontius of Jerusalem, the Grammarian allows for a second meaning, that of true existence. Thus, he accepts the axiom that all ousiai are 'enhypostatic' as long as this means that they really exist. Only in this sense does he agree to call Christ's human ousia 'enhypostatic': in so far as it subsists in the Logos' one Hypostasis and therefore truly exists.

Pavouris (2001) [2], on Leontius of Jerusalem

Leontius makes absolutely clear that only the divine nature has always had its own hypostasis. The human nature, however, has never had a hypostasis of its own. An obvious question is raised by the 'Nestorian': [...] if having a hypostasis primarily means being real - an assumption that Leontius accepts - will a human nature without a hypostasis not be 'anhypostatic', i.e. non existing? Leontius replies that one should distinguish between

a) 'anhypostaton', i.e. something that does not have a hypostasis at all,
b) 'idiohypostaton', i.e. something that exists in its own hypostasis, and
c) 'enhypostaton', i.e. something that subsists in somebody else's hypostasis on account of their union.

Christ's human nature is neither 'anhypostatic' nor 'idiohypostatic'; it is 'enhypostatic', that is, it exists in the pre-existent hypostasis of the Logos. [...] It is not true, says Leontius, that the 'specific human nature' of Christ preceded its hypostasis. [...] As soon it came into being the human nature was enhypostasised, not in a hypostasis of itw own but in the pre-existent hypostasis of the Logos.

End of quote from Pavouris (2001) [2].

This is as close as one can get to understanding the hypostatic union without assuming the real distinction between essence and act of being or existence. To note, even within Thomism the real distinction is always a postulate, an axiom. Twetten [4], in the best treatment of this subject that I am aware of, concludes that "All nine of Aquinas' arguments for the Real Distinction that we have reviewed seem vulnerable to the Question-Begging Objection. Aquinas seems never to have been aware of the objection." (p. 80). He then proposes an argument of his own, based on hylemorphic theory (pp. 85ff). That argument is of no use to me, first because I hold that hylemorphism is a valid description of entities only when the form in question is spiritual, such as the human soul, and secondly because I also hold that the human soul after death is the same person it was with the body, even though in a diminished state, so that his argument would not work for me even in the case of human natures.

Assuming the real distinction between essence and act of being, we can make a general definition of hypostasis that applies to both divine Persons and contingent entities and can be used to formulate the dogmas of trinitarian and christological orthodoxy.

Recalling that hypostasis meant the individual, particular, concrete, really existing subject or "hypokeimenon", and adopting the particular sense of ousía (M1):

ousía = essence or form in a particular sense
hypostasis = act of being in a particular mode + ousía

act of being = {Subsistent Act of Being (one), contingent act of being (many)}

modes of the Subsistent Act of Being = {fontal plenitude and paternity, filiation, passive spiration or procession}

modes of a contingent act of being = {created} -- or none at all

divine Ousía (one) = Subsistent Act of Being (one) -- per absolute divine simplicity

God the Father = Subsistent Act of Being in fontal plenitude and paternity mode

The Son, before the Incarnation = Subsistent Act of Being in filiation mode

The Son, after the Incarnation = Subsistent Act of Being in filiation mode + Jesus' human ousía

The Holy Spirit = Subsistent Act of Being in passive spiration or procession mode

In contrast:

Peter = Peter's contingent act of being + Peter's human ousía

Thus:

- Jesus is not a human person because his human ousía exists by the Subsistent Act of Being in filiation mode, the Hypostasis of the Son.

- Peter is a human person because his ousía exists by Peter's contingent act of being.

Summarizing:

- In creatures, there is a one-to-one correspondence between created hypostasis and created ousía in the particular sense (M1).

- In the Godhead, three Hypostases are one and the same Ousía (in a numerical identity sense), Each in a different mode.

- After the Incarnation, the Son is one Hypostasis in two ousíai.


References

Section 1

[1] https://en.wiktionary.org/wiki/%CE%B5%E1%BC%B0%CE%BC%CE%AF

[2] https://en.wiktionary.org/wiki/%E1%BD%A4%CE%BD

[3] https://en.wiktionary.org/wiki/%CE%BF%E1%BD%96%CF%83%CE%B1

[4] https://en.wiktionary.org/wiki/%CE%BF%E1%BD%90%CF%83%CE%AF%CE%B1

[5] https://en.wiktionary.org/wiki/%CE%BF%CF%85%CF%83%CE%AF%CE%B1

[6] Studtmann, Paul, "Aristotle's Categories", The Stanford Encyclopedia of Philosophy (Fall 2017 Edition), Edward N. Zalta (ed.)
https://plato.stanford.edu/archives/fall2017/entries/aristotle-categories/

[7] https://en.wiktionary.org/wiki/hupokeimenon

[8] Cohen, S. Marc, "Aristotle's Metaphysics", The Stanford Encyclopedia of Philosophy (Winter 2016 Edition), Edward N. Zalta (ed.)
https://plato.stanford.edu/archives/win2016/entries/aristotle-metaphysics/

[9] Loux, Michael J., "Primary Ousia: an essay on Aristotle's Metaphysics Z and H", Cornell University Press, 2008.
https://books.google.com/books?id=1DOIpuLnrnIC

[10] Cohen, S. Marc, "Z.13: Substances and Universals", 2008.
https://faculty.washington.edu/smcohen/433/Z13Lecture.pdf

Section 2

[1] https://en.wiktionary.org/wiki/%E1%BD%91%CF%80%CF%8C

[2] https://en.wiktionary.org/wiki/%CF%83%CF%84%CE%AC%CF%83%CE%B9%CF%82

[3] https://en.wiktionary.org/wiki/substantia

[4] https://en.wiktionary.org/wiki/sub#Latin

[5] https://en.wiktionary.org/wiki/stans#Latin

[6] https://en.wiktionary.org/wiki/sto#Latin

[7] Ute Possekel, "Evidence of Greek philosophical concepts in the writings of Ephrem the Syrian", Peeters Publishers, Louvain, 1999.
https://books.google.com/books?id=rZ3gGQuJUS4C

Section 3

[1] https://en.wiktionary.org/wiki/%CF%87%CE%B1%CF%81%CE%B1%CE%BA%CF%84%CE%AE%CF%81

[2] Reginald Garrigou-Lagrange, O.P., The Trinity and God the Creator: A Commentary on St. Thomas' Theological Summa, Ia, q. 27-119, 1943, translated by Frederic C. Eckhoff, B. Herder Book Co., 1952. Reprinted by Aeterna Press, 2016.
https://isidore.co/calibre/browse/book/3085
https://www.ewtn.com/library/theology/trinity.htm
https://books.google.com/books?id=yGmkDAAAQBAJ

[3] "Subsistence." New Catholic Encyclopedia. Retrieved March 18, 2018 from Encyclopedia.com.
http://www.encyclopedia.com/religion/encyclopedias-almanacs-transcripts-and-maps/subsistence

[4] https://en.wiktionary.org/wiki/subsisto

[5] https://en.wiktionary.org/wiki/sisto

Section 5

[1] http://www.earlychurchtexts.com/public/creed_of_nicaea_325.htm

[2] http://www.fourthcentury.com/urkunde-24/

[3] https://en.wiktionary.org/wiki/%CF%80%CF%81%CF%8C%CF%83%CF%89%CF%80%CE%BF%CE%BD

Section 6

[1] Thomas G. Weinandy, Athanasius: A Theological Introduction, Ashgate Publishing, 2007.
https://books.google.com/books?id=SGOpA_MjSUgC

[2] https://www.elpenor.org/athanasius/in-illud-omnia.asp?pg=7

[3] Lewis Ayres, Nicaea and Its Legacy: An Approach to Fourth-Century Trinitarian Theology, Oxford University Press, Oxford, Oct 28, 2004.
https://books.google.com/books?id=iT4VDAAAQBAJ

[4] http://www.newadvent.org/fathers/2818.htm

[5] The Letters of Saint Jerome, Aeterna Press, 2016.
https://books.google.com/books?id=iTwIDAAAQBAJ

[6] http://www.newadvent.org/fathers/3001015.htm

[7] http://www.earlychurchtexts.com/main/jerome/jerome_ep_15_tres_hypostases.shtml
For the quoted passage, I used this Latin text to improve the accuracy of the English translation in the previous two references.

Section 7

[1] https://www.elpenor.org/basil/letters-3.asp

[2] https://www.elpenor.org/basil/letters-3.asp?pg=39

[3] https://www.scribd.com/document/212698195/Letter-35

[4] http://www.papalencyclicals.net/councils/ecum02.htm

[5] http://www.papalencyclicals.net/councils/ecum03.htm

[6] Richard Price and Michael Gaddis, The acts of the Council of Chalcedon, Liverpool University Press, 2005.
https://books.google.com/books?id=6IUaOOT1G3UC

[7] Pavouris, Raphael (2001), The condemnation of the Christology of the three chapters in its historical and doctrinal context: the assessment and judgement of Emperor Justinian and the Fifth Ecumenical Council (553). PhD thesis, University of Glasgow.
http://theses.gla.ac.uk/1503/

Section 9

[1] http://www.papalencyclicals.net/councils/ecum03.htm

[2] Pavouris, Raphael (2001), The condemnation of the Christology of the three chapters in its historical and doctrinal context: the assessment and judgement of Emperor Justinian and the Fifth Ecumenical Council (553). PhD thesis, University of Glasgow.
http://theses.gla.ac.uk/1503/

[3] https://en.wikipedia.org/wiki/Fides_quaerens_intellectum

[4] David B. Twetten, Really distinguishing essence from esse. Proceedings of the Society for Medieval Logic and Metaphysics, Volume 6, 2006. Pp 57-94.
http://faculty.fordham.edu/klima/SMLM/PSMLM6/PSMLM6.pdf