attributes expressing necessity or eternity and infinity.
Consequently it is abundantly clear, that an absolutely infinite
being must necessarily be defined as consisting in infinite
attributes, each of which expresses a certain eternal and
infinite essence.
If anyone now ask, by what sign shall he be able to
distinguish different substances, let him read the following
propositions, which show that there is but one substance in the
universe, and that it is absolutely infinite, wherefore such a
sign would be sought in vain.

PROP. XI. God, or substance, consisting of infinite attributes,
of which each expresses eternal and infinite essentiality,
necessarily exists.
Proof.-If this be denied, conceive, if possible, that God
does not exist : then his essence does not involve existence.
But this (Prop. vii.) is absurd. Therefore God necessarily
exists.
Another proof.-Of everything whatsoever a cause or reason
must be assigned, either for its existence, or for its
non-existence-e.g. if a triangle exist, a reason or cause must be
granted for its existence ; if, on the contrary, it does not
exist, a cause must also be granted, which prevents it from
existing, or annuls its existence. This reason or cause must
either be contained in the nature of the thing in question, or be
external to it. For instance, the reason for the non-existence
of a square circle is indicated in its nature, namely, because it
would involve a contradiction. On the other hand, the existence
of substance follows also solely from its nature, inasmuch as its
nature involves existence. (See Prop. vii.)