What did Tertullian mean by the Latin words 'persona' and 'substantia'?


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Here I seek a solution to the puzzle of what Tertullian intended by the Latin words 'substantia' and 'persona' in his seminal allegedly anti-Sabellian work, Adversus Praxean, and whether he made a theological error in his misuse of these words.

His work may be viewed as antithetic to the Catholic trinity in that it divides God's economy into 'trinity' whilst allowing God, synonymous with the Father, to be One. The Catholics consequently accuse Tertullian of preaching 'heresy' (in their eyes): i.e. the subordination of Christ to his Father. Others disagree. Yet there is surely merit in this Catholic analysis for it is Tertullian's divine economy that is defined in terms of three persons/persona in one substance/substantia.

Moreover, given that Tertullian states his intention of rebutting the Sabellian position that God is one person, his seems a manifestly inadequate approach. For if the essence of trinity is economy, the Sabellian may well say that Tertullian reinforces the Sabellian contention in failing to grasp that trinity of economy is the Sabellian trinity.

Economy aside, which I allude to because it seems relevant to the words that he used, Tertullian derived his formulation of three persons/personas in one substance from Jesus' words in John 10:30 "ἐγὼ καὶ ὁ Πατὴρ ἕν ἐσμεν" : I and the Father are one (ἕν = neuter of εἷς “one”). From Jesus' employment of the neuter, Tertullian famously derives his thesis that Jesus meant one substantia (i.e. substance). But is this assumption, which I suppose relies on a Greek substantive in the neuter as abstract or conceptual, completely misconceived?
Chapter 2:

"quasi non sic quoque unus sit omnia dum ex uno omnia, per substantiae scilicet unitatem, et nihilo minus custodiatur [Gk: economy] sacramentum quae unitatem in trinitatem disponit, tres dirigens patrem et filium et spiritum, tres autem non statu sed gradu, nec substantia sed forma, nec potestate sed specie, unius autem substantiae et unius status et unius potestatis, quia unus deus ex quo et gradus isti et formae et species in nomine patris et filii et spiritus sancti deputantur. quomodo numerum sine divisione patiuntur procedentes tractatus demonstrabunt."

"..... as though the one <God> were not all <these things> in this way also, that they are all of the one,
namely by unity of substance, while none the less is guarded the mystery of that economy which disposes the unity into trinity, setting forth Father and Son and Spirit as three, three however not in quality but in sequence, not in substance but in aspect, not in power but in <its> manifestation, yet of one substance and one quality and one power, seeing it is one God from whom those sequences and aspects and manifestations are reckoned out in the name of the Father and the Son and the Holy Spirit. How they admit of plurality without division the discussion will show as it proceeds."

Chapter 22:

"ipsum scilicet esse de quo interrogabant, id est Christum dei. de ovibus etiam suis, quod nemo illas de manu eius eriperet, Pater enim, <inquit>, quod mihi dedit maius est omnibus; et, Ego et pater unum sumus. hic ergo iam gradum volunt figere stulti, immo caeci, qui non videant, primo, Ego et pater, duorum esse significationem; dehinc in novissimo, Sumus, non ex unius esse persona, quod pluraliter dictum est; tum quod Unum sumus, non Unus sumus <dicit>. si enim dixisset Unus sumus, potuisset adiuvare sententiam illorum : unus enim singularis numeri significatio videtur. adhuc cum duo masculini generis unum dicit neutrali verbo - quod non pertinet ad singularitatem, sed ad unitatem, ad similitudinem, ad coniunctionem, ad dilectionem patris qui filium diligit, et ad obsequium filii qui voluntati patris obsequitur - Unum sumus, dicens, ego et pater, ostendit duos esse quos aequat et iungit. "

"And concerning his sheep, that no one would snatch them from his hand, he says, For what the Father hath given me is greater than <they> all; and, I and the Father are one. Here then they wish to make a stand, these fools, yea blind, who see not, first, that "I and the Father" is an indication of two; secondly, at the end <of the sentence>, that "are" is not from the person of one, because it is, spoken in the plural; and then, that he says "are one <thing>", not "are one <person> ". For if he had said "are one <person> " he would have been able to assist their (i.e. the Sabellians') case: for "one <person>" is apparently an indication of the singular number. Yet when he says that two, of the masculine gender, are one <thing>, in the neuter-which is not concerned with singularity but with unity, with similitude, with conjunction, with the love of the Father who loveth the Son, and with the obedience of the Son who obeys the Father's will-when he says, One <thing> are I and the Father, he shows that those whom he equates and conjoins are two."

Chapter 25:

Post Philippum et totam substantiam quaestionis istius, quae in finem evangelii perseverant in eodem genere sermonis, quo pater et filius in sua proprietate distinguuntur. paracletum quoque a patre se postulaturum, cum ascendisset ad patrem, et missurum repromittit, et quidem alium. sed iam praemisimus quomodo alium. ceterum, De meo sumet, inquit, sicut ipse de patris. ita connexus patris in filio et filii in paracleto tres efficit cohaerentes alterum ex altero. qui tres unum sunt, non unus, quomodo dictum est, Ego et pater unum sumus, ad substantiae unitatem non ad numeri singularitatem.

"After Philip and the whole context of that question, the things which <follow> down to the end of the gospel continue in the same kind of discourse, in which the Father and the Son are distinguished as being each himself. He promises that when he has ascended to the Father he will also request of the Father the Paraclete, and will send him, <specifying> another. But we have already explained in what sense the means "another". Moreover he says, He will take of mine, 3 as I myself have taken of the Father's. So the close series of the Father in the Son and the Son in the Paraclete makes three who cohere, the one attached to the other:
And these three are one <thing>, not one <person>,
in the sense in which it was said, I and the Father are one, in respect of unity of substance, not of singularity of number.


In Adversus Praxean 'substantia' is inherently antithetic to the usage of the Latin 'persona', just because of the Tertullian formulae "three persons in a unity substance". Yet there are two problems. First, the Deut 6:4 conception of God is that God is one person or a unity or personas ("Audi, Israel: Dominus Deus noster, Dominus unus est" - hear O Israel the Lord our God is one <person/persona>"). Secondly, the ordinary English words 'substance' and person' do not necessarily embrace the antithetic usage in Adversus Praxean, because different persons can have different substances. It is only in certain matters that humans have identical substances (e.g. all men are mortal):

In the Latin dictionary, substantia is defined similarly to the English word properties, i.e.
  • nature
  • substance, resources, wealth, possessions.
However the Latin usage of substantia extends to other English words, in particular hypostasis (Gk: ὑπόστασις - Heb 1:3 - "The Son has the 'imprint/facsimile of the hypostasis of God'"). So it could be argued that God has multiple identical hypostases.

Persona in the Latin dictionary is defined similarly to the English word persona, i.e.
  • mask
  • character, personage, role
  • personality, character, individuality
Persona also translates to face (Gk: πρόσωπον - prosopon - 2 Cor 4:6 "For God, who commanded the light to shine out of darkness, hath shined in our hearts, to give the light of the knowledge of the glory of God in the face of Jesus Christ"). Here the persona of Christ is identified with the knowledge of the glory of God. In this sense, it could be argued that God has one persona that is reflected in both Jesus and the Holy Spirit. For Jesus said to Philip "if you have seen me you have seen the Father" (Jn 14:9).

In the sense of the Greek words hypostasis and prosopon, it is arguable that God presents essentially one prosopon and one hypostasis where both are replicated in Christ and the Holy Spirit. The term "my face (prosopon)" in reference to God (YHWH) occurs 57 times in the Old Testament.

Could not God be more realistically said to (a) manifest one persona (Latin) in three substantia (Latin) , rather than three persona (Latin) in one substantia (Latin), (b) imbue the imprint of his prosopon and his hypostasis in the Holy Spirit and in the Son?

Did Tertullian completely misunderstand the Greek in John 10:30. For didn't Jesus really imply"I and the Father are one economy (i.e. not one substance)"? This is deducible from the context of John 10:29 which is the economy of God, "My Father, which gave [my sheep] to me, is greater than all; and no man is able to pluck them out of my Father's hand."
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