Thomas Aquinas, Summa Theologiae

Objection 1: It would seem that "person" is the same as "hypostasis," "subsistence," and "essence." For Boethius says (De Duab. Nat.) that "the Greeks called the individual substance of the rational nature by the name hypostasis." But this with us signifies "person." Therefore "person" is altogether the same as "hypostasis."

Objection 2: Further, as we say there are three persons in God, so we say there are three subsistences in God; which implies that "person" and "subsistence" have the same meaning. Therefore "person" and "subsistence" mean the same.

Objection 3: Further, Boethius says (Com. Praed.) that the Greek {ousia}, which means essence, signifies a being composed of matter and form. Now that which is composed of matter and form is the individual substance called "hypostasis" and "person." Therefore all the aforesaid names seem to have the same meaning.

Objection 4: On the contrary, Boethius says (De Duab. Nat.) that genera and species only subsist; whereas individuals are not only subsistent, but also substand. But subsistences are so called from subsisting, as substance or hypostasis is so called from substanding. Therefore, since genera and species are not hypostases or persons, these are not the same as subsistences.

Objection 5: Further, Boethius says (Com. Praed.) that matter is called hypostasis, and form is called {ousiosis}---that is, subsistence. But neither form nor matter can be called person. Therefore person differs from the others.

I answer that, According to the Philosopher (Metaph. v), substance is twofold. In one sense it means the quiddity of a thing, signified by its definition, and thus we say that the definition means the substance of a thing; in which sense substance is called by the Greeks {ousia}, what we may call "essence." In another sense substance means a subject or "suppositum," which subsists in the genus of substance. To this, taken in a general sense, can be applied a name expressive of an intention; and thus it is called "suppositum." It is also called by three names signifying a reality---that is, "a thing of nature," "subsistence," and "hypostasis," according to a threefold consideration of the substance thus named. For, as it exists in itself and not in another, it is called "subsistence"; as we say that those things subsist which exist in themselves, and not in another. As it underlies some common nature, it is called "a thing of nature"; as, for instance, this particular man is a human natural thing. As it underlies the accidents, it is called "hypostasis," or "substance." What these three names signify in common to the whole genus of substances, this name "person" signifies in the genus of rational substances.

Reply to Objection 1: Among the Greeks the term "hypostasis," taken in the strict interpretation of the word, signifies any individual of the genus substance; but in the usual way of speaking, it means the individual of the rational nature, by reason of the excellence of that nature.

Reply to Objection 2: As we say "three persons" plurally in God, and "three subsistences," so the Greeks say "three hypostases." But because the word "substance," which, properly speaking, corresponds in meaning to "hypostasis," is used among us in an equivocal sense, since it sometimes means essence, and sometimes means hypostasis, in order to avoid any occasion of error, it was thought preferable to use "subsistence" for hypostasis, rather than "substance."

Reply to Objection 3: Strictly speaking, the essence is what is expressed by the definition. Now, the definition comprises the principles of the species, but not the individual principles. Hence in things composed of matter and form, the essence signifies not only the form, nor only the matter, but what is composed of matter and the common form, as the principles of the species. But what is composed of this matter and this form has the nature of hypostasis and person. For soul, flesh, and bone belong to the nature of man; whereas this soul, this flesh and this bone belong to the nature of this man. Therefore hypostasis and person add the individual principles to the idea of essence; nor are these identified with the essence in things composed of matter and form, as we said above when treating of divine simplicity (Question 3, Article 3).

Reply to Objection 4: Boethius says that genera and species subsist, inasmuch as it belongs to some individual things to subsist, from the fact that they belong to genera and species comprised in the predicament of substance, but not because the species and genera themselves subsist; except in the opinion of Plato, who asserted that the species of things subsisted separately from singular things. To substand, however, belongs to the same individual things in relation to the accidents, which are outside the essence of genera and species.

Reply to Objection 5: The individual composed of matter and form substands in relation to accident from the very nature of matter. Hence Boethius says (De Trin.): "A simple form cannot be a subject." Its self-subsistence is derived from the nature of its form, which does not supervene to the things subsisting, but gives actual existence to the matter and makes it subsist as an individual. On this account, therefore, he ascribes hypostasis to matter, and {ousiosis}, or subsistence, to the form, because the matter is the principle of substanding, and form is the principle of subsisting.

Articulus 2

Argumentum 1

Ad secundum sic proceditur. Videtur quod persona sit idem quod hypostasis, subsistentia et essentia.

Dicit enim boetius, in libro de duab. Natur., quod Graeci naturae rationalis individuam substantiam hypostaseos nomine vocaverunt.

Sed hoc etiam, apud nos, significat nomen personae.

Ergo persona omnino idem est quod hypostasis.

Argumentum 2

Praeterea, sicut in divinis dicimus tres personas, ita in divinis dicimus tres subsistentias, quod non esset, nisi persona et subsistentia idem significarent.

Ergo idem significant persona et subsistentia.

Argumentum 3

Praeterea, boetius dicit, in commento praedicamentorum, quod usia, quod est idem quod essentia, significat compositum ex materia et forma.

Id autem quod est compositum ex materia et forma, est individuum substantiae, quod et hypostasis et persona dicitur.

Ergo omnia praedicta nomina idem significare videntur.

Sed Contra 1

Sed contra est quod boetius dicit, in libro de duab. Natur., quod genera et species subsistunt tantum; individua vero non modo subsistunt, verum etiam substant.

Sed a subsistendo dicuntur subsistentiae, sicut a substando substantiae vel hypostases. Cum igitur esse hypostases vel personas non conveniat generibus vel speciebus, hypostases vel personae non sunt idem quod subsistentiae.

Sed Contra 2

Hypostasis dicitur materia, usiosis autem, idest subsistentia, dicitur forma.

Sed neque forma neque materia potest dici persona.

Ergo persona differt a praedictis.

Corpus

Respondeo dicendum quod, secundum philosophum, in V metaphys., substantia dicitur dupliciter. Uno modo dicitur substantia quidditas rei, quam significat definitio, secundum quod dicimus quod definitio significat substantiam rei, quam quidem substantiam Graeci usiam vocant, quod nos essentiam dicere possumus. Alio modo dicitur substantia subiectum vel suppositum quod subsistit in genere substantiae.

Et hoc quidem, communiter accipiendo, nominari potest et nomine significante intentionem, et sic dicitur suppositum. Nominatur etiam tribus nominibus significantibus rem, quae quidem sunt res naturae, subsistentia et hypostasis, secundum triplicem considerationem substantiae sic dictae. Secundum enim quod per se existit et non in alio, vocatur subsistentia, illa enim subsistere dicimus, quae non in alio, sed in se existunt.

Secundum vero quod supponitur alicui naturae communi, sic dicitur res naturae; sicut hic homo est res naturae humanae.

Secundum vero quod supponitur accidentibus, dicitur hypostasis vel substantia. Quod autem haec tria nomina significant communiter in toto genere substantiarum, hoc nomen persona significat in genere rationalium substantiarum.

Ad 1

Ad primum ergo dicendum quod hypostasis, apud Graecos, ex propria significatione nominis habet quod significet quodcumque individuum substantiae, sed ex usu loquendi habet quod sumatur pro individuo rationalis naturae, ratione suae excellentiae.

Ad 2

Ad secundum dicendum quod, sicut nos dicimus in divinis pluraliter tres personas et tres subsistentias, ita Graeci dicunt tres hypostases.

Sed quia nomen substantiae, quod secundum proprietatem significationis respondet hypostasi, aequivocatur apud nos, cum quandoque significet essentiam, quandoque hypostasim; ne possit esse erroris occasio, maluerunt pro hypostasi transferre subsistentiam, quam substantiam.

Ad 3

Ad tertium dicendum quod essentia proprie est id quod significatur per definitionem. Definitio autem complectitur principia speciei, non autem principia individualia. Unde in rebus compositis ex materia et forma, essentia significat non solum formam, nec solum materiam, sed compositum ex materia et forma communi, prout sunt principia speciei. Sed compositum ex hac materia et ex hac forma, habet rationem hypostasis et personae, anima enim et caro et os sunt de ratione hominis, sed haec anima et haec caro et hoc os sunt de ratione huius hominis.

Et ideo hypostasis et persona addunt supra rationem essentiae principia individualia; neque sunt idem cum essentia in compositis ex materia et forma, ut supra dictum est, cum de simplicitate divina ageretur.

Ad 4

Ad quartum dicendum quod boetius dicit genera et species subsistere, inquantum individuis aliquibus competit subsistere, ex eo quod sunt sub generibus et speciebus in praedicamento substantiae comprehensis, non quod ipsae species vel genera subsistant, nisi secundum opinionem Platonis, qui posuit species rerum separatim subsistere a singularibus.

Substare vero competit eisdem individuis in ordine ad accidentia, quae sunt praeter rationem generum et specierum.

Ad 5

Ad quintum dicendum quod individuum compositum ex materia et forma, habet quod substet accidenti, ex proprietate materiae.

Unde et boetius dicit, in libro de Trin., forma simplex subiectum esse non potest.

Sed quod per se subsistat, habet ex proprietate suae formae, quae non advenit rei subsistenti, sed dat esse actuale materiae, ut sic individuum subsistere possit.

Propter hoc ergo hypostasim attribuit materiae, et usiosim, sive subsistentiam, formae, quia materia est principium substandi, et forma est principium subsistendi.