Chapter III

Now God differs from God in no respect, for there cannot be divine
essences distinguished either by accidents or by substantial differences
belonging to a substrate. But where there is no difference, there is no
sort of plurality and accordingly no number; here, therefore, is unity
alone. For whereas we say God thrice when we name the Father, Son, and
Holy Spirit, these three unities do not produce a plurality of number in
their own essences, if we think of what we count instead of what we
count with. For in the case of abstract number a repetition of single
items does produce plurality; but in the case of concrete number the
repetition and plural use of single items does not by any means produce
numerical difference in the objects counted. There are as a fact two
kinds of number. There is the number with which we count (abstract) and
the number inherent in the things counted (concrete). "One" is a thing--
the thing counted. Unity is that by which oneness is denoted. Again
"two" belongs to the class of things as men or stones; but not so
duality; duality is merely that whereby two men or two stones are
denoted; and so on. Therefore a repetition of unities[17] produces
plurality when it is a question of abstract, but not when it is a
question of concrete things, as, for example, if I say of one and the
same thing, "one sword, one brand, one blade."[18] It is easy to see
that each of these names denotes a sword; I am not numbering unities but
simply repeating one thing, and in saying "sword, brand, blade," I
reiterate the one thing and do not enumerate several different things
any more than I produce three suns instead of merely mentioning one
thing thrice when I say "Sun, Sun, Sun."

So then if God be predicated thrice of Father, Son, and Holy Spirit, the
threefold predication does not result in plural number. The risk of
that, as has been said, attends only on those who distinguish Them
according to merit. But Catholic Christians, allowing no difference of
merit in God, assuming Him to be Pure Form and believing Him to be
nothing else than His own essence, rightly regard the statement "the
Father is God, the Son is God, the Holy Spirit is God, and this Trinity
is one God," not as an enumeration of different things but as a
reiteration of one and the same thing, like the statement, "blade and
brand are one sword" or "sun, sun, and sun are one sun."

Let this be enough for the present to establish my meaning and to show
that not every repetition of units produces number and plurality. Still
in saying "Father, Son, and Holy Spirit," we are not using synonymous
terms. "Brand and blade" are the same and identical, but "Father, Son,
and Holy Spirit," though the same, are not identical. This point
deserves a moment's consideration. When they ask "Is the Father the same
as the Son?" Catholics answer "No." "Is the One the same as the Other?"
The answer is in the negative. There is not, therefore, complete
indifference between Them; and so number does come in--number which we
explained was the result of diversity of substrates. We will briefly
debate this point when we have done examining how particular predicates
can be applied to God.

[17] e.g. if I say "one, one, one," I enounce three unities.

[18] The same words are used to illustrate the same matter in the
_Comment. in Arist._ [Greek: peri hermaeneias], 2nd ed. (Meiser) 56. 12.