Reply Obj. 3: That which now is, was future, before it (actually)
was; because it was in its cause that it would be. Hence, if the
cause were removed, that thing's coming to be was not future. But the
first cause is alone eternal. Hence it does not follow that it was
always true that what now is would be, except in so far as its future
being was in the sempiternal cause; and God alone is such a cause.

Reply Obj. 4: Because our intellect is not eternal, neither is the
truth of enunciable propositions which are formed by us, eternal, but
it had a beginning in time. Now before such truth existed, it was not
true to say that such a truth did exist, except by reason of the
divine intellect, wherein alone truth is eternal. But it is true now
to say that that truth did not then exist: and this is true only by
reason of the truth that is now in our intellect; and not by reason
of any truth in the things. For this is truth concerning not-being;
and not-being has not truth of itself, but only so far as our
intellect apprehends it. Hence it is true to say that truth did not
exist, in so far as we apprehend its not-being as preceding its being.
_______________________

EIGHTH ARTICLE [I, Q. 16, Art. 8]

Whether Truth Is Immutable?

Objection 1: It seems that truth is immutable. For Augustine says (De
Lib. Arbit. ii, 12), that "Truth and mind do not rank as equals,
otherwise truth would be mutable, as the mind is."

Obj. 2: Further, what remains after every change is immutable; as
primary matter is unbegotten and incorruptible, since it remains after
all generation and corruption. But truth remains after all change; for
after every change it is true to say that a thing is, or is not.
Therefore truth is immutable.

Obj. 3: Further, if the truth of an enunciation changes, it changes
mostly with the changing of the thing. But it does not thus change.
For truth, according to Anselm (De Verit. viii), "is a certain
rightness" in so far as a thing answers to that which is in the
divine mind concerning it. But this proposition that "Socrates sits",
receives from the divine mind the signification that Socrates does
sit; and it has the same signification even though he does not sit.
Therefore the truth of the proposition in no way changes.

Obj. 4: Further, where there is the same cause, there is the same
effect. But the same thing is the cause of the truth of the three
propositions, "Socrates sits, will sit, sat." Therefore the tr