AstroAg17 said:
Why do you say each angel is a unique species?
Summa Theologica
http://www.newadvent.org/summa/1050.htm"Article 4. Whether the angels differ in species?
Objection 1. It would seem that the
angels do not differ in
species. For since the "difference" is nobler than the 'genus,' all things which agree in what is noblest in them, agree likewise in their ultimate constitutive difference; and so they are the same according to
species. But all
angels agree in what is noblest in them--that is to say, in intellectuality. Therefore all the
angels are of one
species.
Objection 2. Further, more and less do not change a
species. But the
angels seem to differ only from one another according to more and less--namely, as one is simpler than another, and of keener
intellect. Therefore the
angels do not differ specifically.
Objection 3. Further,
soul and
angel are contra-distinguished mutually from each other. But all
souls are of the one
species. So therefore are the
angels.
Objection 4. Further, the more perfect a thing is in
nature, the more ought it to be multiplied. But this would not be so if there were but one
individual under one
species. Therefore there are many
angels of one
species.
On the contrary, In things of one
species there is no such thing as "first" and "second" [prius et posterius], as the
Philosopher says (Metaph. iii, text 2). But in the
angels even of the one order there are first, middle, and last, as
Dionysius says (Hier. Ang. x). Therefore the
angels are not of the same
species.
I answer that, Some have said that all
spiritual substances, even
souls, are of the one
species. Others, again, that all the
angels are of the one
species, but not
souls; while others allege that all the
angels of one
hierarchy, or even of one order, are of the one
species.
But this is impossible. For such things as agree in
species but differ in number, agree in
form, but are distinguished materially. If, therefore, the
angels be not composed of
matter and
form, as was said above (
Article 2), it follows that it is impossible for two
angels to be of one
species; just as it would be impossible for there to be several whitenesses apart, or several humanities, since whitenesses are not several, except in so far as they are in several
substances. And if the
angels had
matter, not even then could there be several
angels of one
species. For it would be
necessary for
matter to be the principle of distinction of one from the other, not, indeed, according to the division of
quantity, since they are incorporeal, but according to the diversity of their powers; and such diversity of
matter causes diversity not merely of
species, but of genus.
Reply to Objection 1. "Difference" is nobler than "genus," as the determined is more noble than the undetermined, and the proper than the common, but not as one
nature is nobler than another; otherwise it would be
necessary that all irrational animals be of the same
species; or that there should be in them some form which is higher than the sensible
soul. Therefore irrational animals differ in
species according to the various determined degrees of sensitive
nature; and in like manner all the
angels differ in
species according to the diverse degrees of
intellectual nature.
Reply to Objection 2. More and less change the
species, not according as they are
caused by the intensity or remissness of one form, but according as they are
caused by forms of diverse degrees; for instance, if we say that fire is more perfect than air: and in this way the
angels are diversified according to more or less.
Reply to Objection 3. The
good of the
species preponderates over the
good of the
individual. Hence it is much better for the
species to be multiplied in the
angels than for
individuals to be multiplied in the one
species.
Reply to Objection 4. Numerical multiplication, since it can be drawn out
infinitely, is not intended by the agent, but only specific multiplication, as was said above (
I:47:3). Hence the perfection of the
angelic nature calls for the multiplying of
species, but not for the multiplying of
individuals in one
species."