ll. I.--Hence it follows that God's existence, like his
essence, is an eternal truth.

Coroll. II--Secondly, it follows that God, and all the
attributes of God, are unchangeable. For if they could be
changed in respect to existence, they must also be able to be
changed in respect to essence--that is, obviously, be changed from
true to false, which is absurd.

PROP. XXI. All things which follow from the absolute nature of
any attribute of God must always exist and be infinite, or, in
other words, are eternal and infinite through the said attribute.

Proof.--Conceive, if it be possible (supposing the proposition
to be denied), that something in some attribute of God can follow
from the absolute nature of the said attribute, and that at the
same time it is finite, and has a conditioned existence or
duration; for instance, the idea of God expressed in the
attribute thought. Now thought, in so far as it is supposed to
be an attribute of God, is necessarily (by Prop. xi.) in its
nature infinite. But, in so far as it possesses the idea of God,
it is supposed finite. It cannot, however, be conceived as
finite, unless it be limited by thought (by Def. ii.); but it is
not limited by thought itself, in so far as it has constituted
the idea of God (for so far it is supposed to be finite);
therefore, it is limited by thought, in so far as it has not
constituted the idea of God, which nevertheless (by Prop. xi.)
must necessarily exist.

We have now granted, therefore, thought not constituting the
idea of God, and, accordingly, the idea of God does not naturally
follow from its nature in so far as it is absolute thought (for
it is conceived as constituting, and also as not constituting,
the idea of God), which is against our hypothesis. Wherefore, if
the idea of God expressed in the attribute thought, or, indeed,
anything else in any attribute of God (for we may take any
example, as the proof is of universal application) follows from
the necessity of the absolute nature of the said attribute, the
said thing must necessarily be infinite, which was our first
point.

Furthermore, a thing which thus follows from the necessity of
the nature of any attribute cannot have a limited duration. For
if it can, suppose a thing, which follows from the necessity of
the nature of some attribute, to exist in some attribute of God,
for instance, the idea of God expressed in the attribute thought,
and let it be supposed at some time not t