n did not take place in the
hypostasis or suppositum. Hence in the same Synod (can. 2) it is
said: "If anyone does not confess that the Word was united to flesh
in subsistence, and that Christ with His flesh is both--to wit, God
and man--let him be anathema."

Reply Obj. 1: As accidental difference makes a thing "other"
(_alterum_), so essential difference makes "another thing" (_aliud_).
Now it is plain that the "otherness" which springs from accidental
difference may pertain to the same hypostasis or suppositum in
created things, since the same thing numerically can underlie
different accidents. But it does not happen in created things that
the same numerically can subsist in divers essences or natures. Hence
just as when we speak of "otherness" in regard to creatures we do not
signify diversity of suppositum, but only diversity of accidental
forms, so likewise when Christ is said to be one thing or another
thing, we do not imply diversity of suppositum or hypostasis, but
diversity of nature. Hence Gregory Nazianzen says in a letter to
Chelidonius (Ep. ci): "In the Saviour we may find one thing and
another, yet He is not one person and another. And I say 'one thing
and another'; whereas, on the contrary, in the Trinity we say one
Person and another (so as not to confuse the subsistences), but not
one thing and another."

Reply Obj. 2: Hypostasis signifies a particular substance, not in
every way, but as it is in its complement. Yet as it is in union with
something more complete, it is not said to be a hypostasis, as a hand
or a foot. So likewise the human nature in Christ, although it is a
particular substance, nevertheless cannot be called a hypostasis or
suppositum, seeing that it is in union with a completed thing, viz.
the whole Christ, as He is God and man. But the complete being with
which it concurs is said to be a hypostasis or suppositum.

Reply Obj. 3: In created things a singular thing is placed in a genus
or species, not on account of what belongs to its individuation, but
on account of its nature, which springs from its form, and in
composite things individuation is taken more from matter. Hence we
say that Christ is in the human species by reason of the nature
assumed, and not by reason of the hypostasis.
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FOURTH ARTICLE [III, Q. 2, Art. 4]

Whether After the Incarnation the Person or Hypostasis of Christ Is
Composite?

Objection 1: It would seem that the Person of Christ