PROOF.
For, grant that composite substances do not consist of
simple parts;
in this case, if all combination or composition were annihilated in
thought, no composite part, and (as, by the supposition, there do
not exist simple parts) no simple part would exist. Consequently, no
substance; consequently, nothing would exist. Either, then, it is
impossible to annihilate composition in thought; or, after such
annihilation, there must remain something that subsists without
composition, that is, something that is simple. But in the former case
the composite could not itself consist of substances, because with
substances composition is merely a contingent relation, apart from
which they must still exist as self—subsistent beings. Now, as this
case contradicts the supposition, the second must contain the truth—
that the substantial composite in the world consists of simple parts.
It follows, as an immediate inference, that the things in the
world are all, without exception, simple beings— that composition is
merely an external condition pertaining to them— and that, although we
never can separate and isolate the elementary substances from the
state of composition, reason must cogitate these as the primary
subjects of all composition,
and consequently, as prior thereto— and
as simple substances.
