ure of the species. But there is nothing
nobler either in an angel or in the soul than their intellectual
nature. Therefore the soul and the angel agree in the ultimate
specific difference: therefore they belong to the same species.

Obj. 3: Further, it seems that the soul does not differ from an angel
except in its union with the body. But as the body is outside the
essence of the soul, it seems that it does not belong to its species.
Therefore the soul and angel are of the same species.

_On the contrary,_ Things which have different natural operations are
of different species. But the natural operations of the soul and of
an angel are different; since, as Dionysius says (Div. Nom. vii),
"Angelic minds have simple and blessed intelligence, not gathering
their knowledge of Divine things from visible things." Subsequently
he says the contrary to this of the soul. Therefore the soul and an
angel are not of the same species.

_I answer that,_ Origen (Peri Archon iii, 5) held that human souls
and angels are all of the same species; and this because he supposed
that in these substances the difference of degree was accidental, as
resulting from their free-will: as we have seen above (Q. 47, A. 2).
But this cannot be; for in incorporeal substances there cannot be
diversity of number without diversity of species and inequality of
nature; because, as they are not composed of matter and form, but are
subsistent forms, it is clear that there is necessarily among them a
diversity of species. For a separate form cannot be understood
otherwise than as one of a single species; thus, supposing a separate
whiteness to exist, it could only be one; forasmuch as one whiteness
does not differ from another except as in this or that subject. But
diversity of species is always accompanied with a diversity of
nature; thus in species of colors one is more perfect than another;
and the same applies to other species, because differences which
divide a genus are contrary to one another. Contraries, however, are
compared to one another as the perfect to the imperfect, since the
"principle of contrariety is habit, and privation thereof," as is
written, _Metaph._ x (Did. ix, 4). The same would follow if the
aforesaid substances were composed of matter and form. For if the
matter of one be distinct from the matter of another, it follows that
either the form is the principle of the distinction of matter--that
is to say, that the matter is distinct o