wered these
questions--namely, if a true idea is distinguished from a false
idea, only in so far as it is said to agree with its object, a
true idea has no more reality or perfection than a false idea
(since the two are only distinguished by an extrinsic mark);
consequently, neither will a man who has a true idea have any
advantage over him who has only false ideas. Further, how comes
it that men have false ideas? Lastly, how can anyone be sure,
that he has ideas which agree with their objects? These
questions, I repeat, I have, in my opinion, sufficiently
answered. The difference between a true idea and a false idea is
plain: from what was said in II. xxxv., the former is related to
the latter as being is to not--being. The causes of falsity I
have set forth very clearly in II. xix. and II. xxxv. with the
note. From what is there stated, the difference between a man
who has true ideas, and a man who has only false ideas, is made
apparent. As for the last question--as to how a man can be sure
that he has ideas that agree with their objects, I have just
pointed out, with abundant clearness, that his knowledge arises
from the simple fact, that he has an idea which corresponds with
its object--in other words, that truth is its own standard. We
may add that our mind, in so far as it perceives things truly, is
part of the infinite intellect of God (II. xi. Coroll.);
therefore, the clear and distinct ideas of the mind are as
necessarily true as the ideas of God.

PROP. XLIV. It is not in the nature of reason to regard things
as contingent, but as necessary.

Proof.--It is in the nature of reason to perceive things truly
(II. xli.), namely (I. Ax. vi.), as they are in themselves--that
is (I. xxix.), not as contingent, but as necessary. Q.E.D.

Corollary I.--Hence it follows, that it is only through our
imagination that we consider things, whether in respect to the
future or the past, as contingent.

Note.--How this way of looking at things arises, I will
briefly explain. We have shown above (II. xvii. and Coroll.)
that the mind always regards things as present to itself, even
though they be not in existence, until some causes arise which
exclude their existence and presence. Further (II. xviii.), we
showed that, if the human body has once been affected by two
external bodies simultaneously, the mind, when it afterwards
imagines one of the said external bodies, will straightway
remember the other--that is, i