But the proper definition of Person is a matter of very great
perplexity. For if every nature has person, the difference between
nature and person is a hard knot to unravel; or if person is not taken
as the equivalent of nature but is a term of less scope and range, it is
difficult to say to what natures it may be extended, that is, to what
natures the term person may be applied and what natures are dissociate
from it. For one thing is clear, namely that nature is a substrate of
Person, and that Person cannot be predicated apart from nature.
We must, therefore, conduct our inquiry into these points as follows.
Since Person cannot exist apart from a nature and since natures are
either substances or accidents and we see that a person cannot come into
being among accidents (for who can say there is any person of white or
black or size?), it therefore remains that Person is properly applied to
substances. But of substances, some are corporeal and others
incorporeal. And of corporeals, some are living and others the reverse;
of living substances, some are sensitive and others insensitive; of
sensitive substances, some are rational and others irrational.[58]
Similarly of incorporeal substances, some are rational, others the
reverse (for instance the animating spirits of beasts); but of rational
substances there is one which is immutable and impassible by nature,
namely God, another which in virtue of its creation is mutable and
passible except in that case where the Grace of the impassible substance
has transformed it to the unshaken impassibility which belongs to angels
and to the soul.
Now from all the definitions we have given it is clear that Person
cannot be affirmed of bodies which have no life (for no one ever said
that a stone had a person), nor yet of living things which lack sense
(for neither is there any person of a tree), nor finally of that which
is bereft of mind and reason (for there is no person of a horse or ox or
any other of the animals which dumb and unreasoning live a life of sense
alone), but we say there is a person of a man, of God, of an angel.
Again, some substances are universal, others are particular. Universal
terms are those which are predicated of individuals, as man, animal,
stone, stock and other things of this kind which are either genera or
species; for the term man is applied to individual men just as animal is
to individual animals, and stone and stock to individual stones and
stocks. But particulars are terms which are never predicated of other
things, as Cicero, Plato, this stone from which this statue of Achilles
was hewn, this piece of wood out of which this table was made. But in
all these things person cannot in any case be applied to universals, but
only to particulars and individuals; for there is no person of a man if
animal or general; only the single persons of Cicero, Plato, or other
single individuals are termed persons.
[58] For a similar example of the method of _diuisio_ cf. Cic. _De Off._
ii. 3. 11. Cf. also _Isag. Porph. edit. prima_, i. 10 (ed. Brandt, p.
29).