understand by
composing and dividing, but only by understanding the essence. Thus it
is evident that for the self-same reason our intellect understands by
discursion, and by composing and dividing, namely, that in the first
apprehension of anything newly apprehended it does not at once grasp
all that is virtually contained in it. And this comes from the
weakness of the intellectual light within us, as has been said
(A. 3). Hence, since the intellectual light is perfect in the
angel, for he is a pure and most clear mirror, as Dionysius says
(Div. Nom. iv), it follows that as the angel does not understand by
reasoning, so neither does he by composing and dividing.

Nevertheless, he understands the composition and the division of
enunciations, just as he apprehends the reasoning of syllogisms: for
he understands simply, such things as are composite, things movable
immovably, and material things immaterially.

Reply Obj. 1: Not every multitude of things understood causes
composition, but a multitude of such things understood that one of
them is attributed to, or denied of, another. When an angel apprehends
the nature of anything, he at the same time understands whatever can
be either attributed to it, or denied of it. Hence, in apprehending a
nature, he by one simple perception grasps all that we can learn by
composing and dividing.

Reply Obj. 2: The various natures of things differ less as to their
mode of existing than do affirmation and negation. Yet, as to the way
in which they are known, affirmation and negation have something more
in common; because directly the truth of an affirmation is known, the
falsehood of the opposite negation is known also.

Reply Obj. 3: The fact that angels use affirmative and negative forms
of speech, shows that they know both composition and division: yet
not that they know by composing and dividing, but by knowing simply
the nature of a thing.
_______________________

FIFTH ARTICLE [I, Q. 58, Art. 5]

Whether There Can Be Falsehood in the Intellect of an Angel?

Objection 1: It would seem that there can be falsehood in the angel's
intellect. For perversity appertains to falsehood. But, as Dionysius
says (Div. Nom. iv), there is "a perverted fancy" in the demons.
Therefore it seems that there can be falsehood in the intellect of
the angels.

Obj. 2: Further, nescience is the cause of estimating falsely. But,
as Dionysius says (Eccl. Hier. vi), there can be nescience in the
ang