Wherefore if Person belongs to substances alone, and these rational, and
if every nature is a substance, existing not in universals but in
individuals, we have found the definition of Person, viz.: "The
individual substance of a rational nature."[60] Now by this definition
we Latins have described what the Greeks call [Greek: hupostasis]. For
the word person seems to be borrowed from a different source, namely
from the masks which in comedies and tragedies used to signify the
different subjects of representation. Now _persona_ "mask" is
derived from _personare_, with a circumflex on the penultimate. But
if the accent is put on the antepenultimate[61] the word will clearly be
seen to come from _sonus_ "sound," and for this reason, that the
hollow mask necessarily produces a larger sound. The Greeks, too, call
these masks [Greek: prosopa] from the fact that they are placed over the
face and conceal the countenance from the spectator: [Greek: para tou
pros tous opas tithesthai]. But since, as we have said, it was by the
masks they put on that actors played the different characters
represented in a tragedy or comedy--Hecuba or Medea or Simon or
Chremes,--so also all other men who could be recognized by their several
characteristics were designated by the Latins with the term
_persona_ and by the Greeks with [Greek: prosopa]. But the Greeks
far more clearly gave to the individual subsistence of a rational nature
the name [Greek: hupostasis] while we through want of appropriate words
have kept a borrowed term, calling that _persona_ which they call
[Greek: hupostasis]; but Greece with its richer vocabulary gives the
name [Greek: hupostasis] to the individual subsistence. And, if I may
use Greek in dealing with matters which were first mooted by Greeks
before they came to be interpreted in Latin: [Greek: hai ousiai en men
tois katholou einai dunantai. en de tois atomois kai kata meros monois
huphistantai], that is: essences indeed can have potential existence in
universals, but they have particular substantial existence in
particulars alone. For it is from particulars that all our comprehension
of universals is taken. Wherefore since subsistences are present in
universals but acquire substance in particulars they rightly gave the
name [Greek: hupostasis] to subsistences which acquired substance
through the medium of particulars. For to no one using his eyes with any
care or penetration will subsistence and substance appear identical.
For our equivalents of the Greek terms [Greek: ousiosis ousiosthai] are
respectively _subsistentia_ and _subsistere_, while their
[Greek: hupostasis huphistasthai] are represented by our
_substantia_ and _substare_. For a thing has subsistence when
it does not require accidents in order to be, but that thing has
substance which supplies to other things, accidents to wit, a substrate
enabling them to be; for it "substands" those things so long as it is
subjected to accidents. Thus genera and species have only subsistence,
for accidents do not attach to genera and species. But particulars have
not only subsistence but substance, for they, no more than generals,
depend on accidents for their Being; for they are already provided with
their proper and specific differences and they enable accidents to be by
supplying them with a substrate. Wherefore _esse_ and
_subsistere_ represent [Greek: einai] and [Greek: ousiosthai],
while _substare_ represents [Greek: huphistasthai]. For Greece is
not, as Marcus Tullius[62] playfully says, short of words, but provides
exact equivalents for _essentia, subsistentia, substantia_ and
_persona_--[Greek: ousia] for _essentia_, [Greek: ousiosis]
for _subsistentia_, [Greek: hupostasis] for _substantia_,
[Greek: prosopon] for _persona_. But the Greeks called individual
substances [Greek: hupostaseis] because they underlie the rest and offer
support and substrate to what are called accidents; and we in our term
call them substances as being substrate--[Greek: hupostaseis], and since
they also term the same substances [Greek: prosopa], we too may call
them persons. So [Greek: ousia] is identical with essence, [Greek:
ousiosis] with subsistence, [Greek: hupostasis] with substance, [Greek:
prosopon] with person. But the reason why the Greek does not use [Greek:
hupostasis] of irrational animals while we apply the term substance to
them is this: This term was applied to things of higher value, in order
that what is more excellent might be distinguished, if not by a
definition of nature answering to the literal meaning of [Greek:
huphistasthai]=_substare_, at any rate by the words [Greek:
hupostasis]=_substantia_.
To begin with, then, man is essence, i.e. [Greek: ousia], subsistence,
i.e. [Greek: ousiosis, hupostasis], i.e. substance, [Greek: prosopon],
i.e. person: [Greek: ousia] or _essentia_ because he is, [Greek:
ousiosis], or subsistence because he is not accidental to any subject,
[Greek: hupostusis] or substance because he is subject to all the things
which are not subsistences or [Greek: ousioseis], while he is [Greek:
prosopon] or person because he is a rational individual. Next, God is
[Greek: ousia], or essence, for He is and is especially that from which
proceeds the Being of all things. To Him belong [Greek: ousiosis], i.e.
subsistence, for He subsists in absolute independence, and [Greek:
huphistasthai], for He is substantial Being. Whence we go on to say that
there is one [Greek: ousia] or [Greek: ousiosis], i.e. one essence or
subsistence of the Godhead, but three [Greek: hupostaseis] or
substances. And indeed, following this use, men have spoken of One
essence, three substances and three persons of the Godhead. For did not
the language of the Church forbid us to say three substances in speaking
of God,[63] substance might seem a right term to apply to Him, not
because He underlies all other things like a substrate, but because,
just as He excels above all things, so He is the foundation and support
of things, supplying them all with [Greek: ousiosthai] or subsistence.
[60] Boethius's definition of _persona_ was adopted by St. Thomas (S. i.
29. 1), was regarded as classical by the Schoolmen, and has the approval
of modern theologians. Cf. Dorner, _Doctrine of Christ_, iii. p. 311.
[61] Implying a short penultimate.
[62] _Tusc._ ii. 15. 35.
[63] For a similar submission of his own opinion to the usage of the
Church cf. the end of _Tr._ i. and of _Tr._ ii.