there are four points of inquiry:

(1) Of their darkness of intellect;

(2) Of their obstinacy of will;

(3) Of their grief;

(4) Of their place of punishment.
_______________________

FIRST ARTICLE [I, Q. 64, Art. 1]

Whether the Demons' Intellect Is Darkened by Privation of the
Knowledge of All Truth?

Objection 1: It would seem that the demons' intellect is darkened by
being deprived of the knowledge of all truth. For if they knew any
truth at all, they would most of all know themselves; which is to
know separated substances. But this is not in keeping with their
unhappiness: for this seems to belong to great happiness, insomuch as
that some writers have assigned as man's last happiness the knowledge
of the separated substances. Therefore the demons are deprived of all
knowledge of truth.

Obj. 2: Further, what is most manifest in its nature, seems to be
specially manifest to the angels, whether good or bad. That the same
is not manifest with regard to ourselves, comes from the weakness of
our intellect which draws its knowledge from phantasms; as it comes
from the weakness of its eye that the owl cannot behold the light of
the sun. But the demons cannot know God, Who is most manifest of
Himself, because He is the sovereign truth; and this is because they
are not clean of heart, whereby alone can God be seen. Therefore
neither can they know other things.

Obj. 3: Further, according to Augustine (Gen. ad lit. iv, 22), the
proper knowledge of the angels is twofold; namely, morning and
evening. But the demons have no morning knowledge, because they do
not see things in the Word; nor have they the evening knowledge,
because this evening knowledge refers the things known to the
Creator's praise (hence, after "evening" comes "morning" [Gen. 1]).
Therefore the demons can have no knowledge of things.

Obj. 4: Further, the angels at their creation knew the mystery of the
kingdom of God, as Augustine says (Gen. ad lit. v, 19; De Civ. Dei
xi). But the demons are deprived of such knowledge: "for if they had
known it, they would never have crucified the Lord of glory," as is
said 1 Cor. 2:8. Therefore, for the same reason, they are deprived of
all other knowledge of truth.

Obj. 5: Further, whatever truth anyone knows is known either
naturally, as we know first principles; or by deriving it from
someone else, as we know by learning; or by long experience, as the
things we learn by discovery. Now, the demons canno