To knowledge of the first kind we have said that all those ideas belong
which are inadequate and confused, and, therefore, this knowledge alone
is the cause of falsity. Moreover, to knowledge of the second and third
kind we have said that those ideas belong which are adequate, and
therefore this knowledge is necessarily true.

It is the knowledge of the second and third, and not that of the first
kind, which teaches us to distinguish the true from the false. For he
who knows how to distinguish between the true and the false must have an
adequate idea of the true and the false, that is to say, he must know
the true and the false by the second or third kind of knowledge.

_Reason and Imagination_

It is in the nature of reason to perceive things truly, that is to say,
as they are in themselves, that is to say, not as contingent but as
necessary.

Hence it follows that it is through the imagination alone that we look
upon things as contingent both with reference to the past and the
future.

How this happens I will explain in a few words. We have shown above that
unless causes occur preventing the present existence of things, the mind
always imagines them present before it, even if they do not exist.
Again, we have shown that if the human body has once been simultaneously
affected by two external bodies, whenever the mind afterwards imagines
one it will immediately remember the other; that is to say, it will
look upon both as present before it, unless causes occur which prevent
the present existence of the things. No one doubts, too, that we imagine
time because we imagine some bodies to move with a velocity less, or
greater than, or equal to that of others.

Let us therefore suppose a boy who yesterday, for the first time, in the
morning saw Peter, at midday Paul, in the evening Simeon, and to-day in
the morning again sees Peter. It is plain that as soon as he sees the
morning light he will imagine the sun passing through the same part of
the sky as on the day preceding; that is to say, he will imagine the
whole day, and at the same time Peter will be connected in his
imagination with the morning, Paul with midday, and Simeon with the
evening. In the morning, therefore, the existence of Paul and Simeon
will be imagined in relation to future time, while in the evening, if
the boy should see Simeon, he will refer Peter and Paul to the past,
since they will be connected with the past in his imagination. This
proces