Whether "One" Adds Anything to "Being"?
Objection 1: It seems that "one" adds something to "being." For
everything is in a determinate genus by addition to being, which
penetrates all _genera._ But "one" is a determinate genus, for it is
the principle of number, which is a species of quantity. Therefore
"one" adds something to "being."
Obj. 2: Further, what divides a thing common to all, is an
addition to it. But "being" is divided by "one" and by "many."
Therefore "one" is an addition to "being."
Obj. 3: Further, if "one" is not an addition to "being," "one"
and "being" must have the same meaning. But it would be nugatory to
call "being" by the name of "being"; therefore it would be equally so
to call being "one." Now this is false. Therefore "one" is an addition
to "being."
_On the contrary,_ Dionysius says (Div. Nom. 5, ult.): "Nothing which
exists is not in some way one," which would be false if "one" were an
addition to "being," in the sense of limiting it. Therefore "one" is
not an addition to "being."
_I answer that,_ "One" does not add any reality to "being"; but is only
a negation of division; for "one" means undivided "being." This is the
very reason why "one" is the same as "being." Now every being is
either simple or compound. But what is simple is undivided, both
actually and potentially. Whereas what is compound, has not being
whilst its parts are divided, but after they make up and compose it.
Hence it is manifest that the being of anything consists in
undivision; and hence it is that everything guards its unity as it
guards its being.
Reply Obj. 1: Some, thinking that the "one" convertible with "being"
is the same as the "one" which is the principle of number, were
divided into contrary opinions. Pythagoras and Plato, seeing that the
"one" convertible with "being" did not add any reality to "being,"
but signified the substance of "being" as undivided, thought that the
same applied to the "one" which is the principle of number. And
because number is composed of unities, they thought that numbers were
the substances of all things. Avicenna, however, on the contrary,
considering that "one" which is the principle of number, added a
reality to the substance of "being" (otherwise number made of unities
would not be a species of quantity), thought that the "one"
convertible with "being" added a reality to the substance of beings;
as "white" to "man." This, however, is manifestly false, inasmuch as
each thing is "one" by its substance. For if a thing were "one" by
anything else but by its substance, since this again would be "one,"
supposing it were again "one" by another thing, we should be driven
on to infinity. Hence we must adhere to the former statement;
therefore we must say that the "one" which is convertible with
"being," does not add a reality to being; but that the "one" which is
the principle of number, does add a reality to "being," belonging to
the genus of quantity.
Reply Obj. 2: There is nothing to prevent a thing which in one way is
divided, from being another way undivided; as what is divided in
number, may be undivided in species; thus it may be that a thing is
in one way "one," and in another way "many." Still, if it is
absolutely undivided, either because it is so according to what
belongs to its essence, though it may be divided as regards what is
outside its essence, as what is one in subject may have many
accidents; or because it is undivided actually, and divided
potentially, as what is "one" in the whole, and is "many" in parts;
in such a case a thing will be "one" absolutely and "many"
accidentally. On the other hand, if it be undivided accidentally, and
divided absolutely, as if it were divided in essence and undivided in
idea or in principle or cause, it will be "many" absolutely and "one"
accidentally; as what are "many" in number and "one" in species or
"one" in principle. Hence in that way, being is divided by "one" and
by "many"; as it were by "one" absolutely and by "many" accidentally.
For multitude itself would not be contained under "being," unless it
were in some way contained under "one." Thus Dionysius says (Div.
Nom., cap. ult.) that "there is no kind of multitude that is not in
a way one. But what are many in their parts, are one in their whole;
and what are many in accidents, are one in subject; and what are many
in number, are one in species; and what are many in species, are one
in genus; and what are many in processions, are one in principle."
Reply Obj. 3: It does not follow that it is nugatory to say
"being" is "one"; forasmuch as "one" adds an idea to "being."
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