external cause. Things which are produced by external causes,
whether they consist of many parts or few, owe whatsoever
perfection or reality they possess solely to the efficacy of
their external cause ; and therefore their existence arises
solely from the perfection of their external cause, not from
their own. Contrrariwise, whatsoever perfection is possessed by
substance is due to no external cause ; wherefore the existence
of substance must arise solely from its own nature, which is
nothing else but its essence. Thus, the perfection of a thing
does not annul its existence, but, on the contrary, asserts it.
Imperfection, on the other hand, does annul it ; therefore we
cannot be more certain of the existence of anything, than of the
existence of a being absolutely infinite or perfect-that is, of
God. For inasmuch as his essence excludes all imperfection, and
involves absolute perfection, all cause for doubt concerning his
existence is done away, and the utmost certainty on the question
is given. This, I think, will be evident to every moderately
attentive reader.

PROP. XII. No attribute of substance can be conceived from which
it would follow that substance can be divided.
Proof.-The parts into which substance as thus conceived would
be divided either will retain the nature of substance, or they
will not. If the former, then (by Prop. viii.) each part will
necessarily be infinite, and (by Prop. vi.) self-caused, and (by
Prop. v.) will perforce consist of a different attribute, so
that, in that case, several substances could be formed out of one
substance, which (by Prop. vi.) is absurd. Moreover, the parts
(by Prop. ii.) would have nothing in common with their whole, and
the whole (by Def. iv. and Prop. x.) could both exist and be