use it imports privation, and every privation is an
imperfection, which cannot apply to God. Therefore God is not one.

_On the contrary,_ It is written "Hear, O Israel, the Lord our God is
one Lord" (Deut. 6:4).

_I answer that,_ It can be shown from these three sources that God is
one. First from His simplicity. For it is manifest that the reason why
any singular thing is "this particular thing" is because it cannot be
communicated to many: since that whereby Socrates is a man, can be
communicated to many; whereas, what makes him this particular man, is
only communicable to one. Therefore, if Socrates were a man by what
makes him to be this particular man, as there cannot be many Socrates,
so there could not in that way be many men. Now this belongs to God
alone; for God Himself is His own nature, as was shown above
(Q. 3, A. 3). Therefore, in the very same way God is God, and He
is this God. Impossible is it therefore that many Gods should exist.

Secondly, this is proved from the infinity of His perfection. For it
was shown above (Q. 4, A. 2) that God comprehends in Himself the
whole perfection of being. If then many gods existed, they would
necessarily differ from each other. Something therefore would belong
to one which did not belong to another. And if this were a privation,
one of them would not be absolutely perfect; but if a perfection, one
of them would be without it. So it is impossible for many gods to
exist. Hence also the ancient philosophers, constrained as it were by
truth, when they asserted an infinite principle, asserted likewise
that there was only one such principle.

Thirdly, this is shown from the unity of the world. For all things
that exist are seen to be ordered to each other since some serve
others. But things that are diverse do not harmonize in the same
order, unless they are ordered thereto by one. For many are reduced
into one order by one better than by many: because one is the _per se_
cause of one, and many are only the accidental cause of one, inasmuch
as they are in some way one. Since therefore what is first is most
perfect, and is so _per se_ and not accidentally, it must be that the
first which reduces all into one order should be only one. And this
one is God.

Reply Obj. 1: Gods are called many by the error of some who
worshipped many deities, thinking as they did that the planets and
other stars were gods, and also the separate parts of the world.
Hence the Apostle adds: