t know the truth
by their own nature, because, as Augustine says (De Civ. Dei xi, 33),
the good angels are separated from them as light is from darkness;
and every manifestation is made through light, as is said Eph. 5:13.
In like manner they cannot learn by revelation, nor by learning from
the good angels: because "there is no fellowship of light with
darkness [*Vulg.: 'What fellowship hath . . . ?']" (2 Cor. 6:14). Nor
can they learn by long experience: because experience comes of the
senses. Consequently there is no knowledge of truth in them.

_On the contrary,_ Dionysius says (Div. Nom. iv) that, "certain gifts
were bestowed upon the demons which, we say, have not been changed at
all, but remain entire and most brilliant." Now, the knowledge of
truth stands among those natural gifts. Consequently there is some
knowledge of truth in them.

_I answer that,_ The knowledge of truth is twofold: one which comes
of nature, and one which comes of grace. The knowledge which comes of
grace is likewise twofold: the first is purely speculative, as when
Divine secrets are imparted to an individual; the other is effective,
and produces love for God; which knowledge properly belongs to the
gift of wisdom.

Of these three kinds of knowledge the first was neither taken away nor
lessened in the demons. For it follows from the very nature of the
angel, who, according to his nature, is an intellect or mind: since on
account of the simplicity of his substance, nothing can be withdrawn
from his nature, so as to punish him by subtracting from his natural
powers, as a man is punished by being deprived of a hand or a foot or
of something else. Therefore Dionysius says (Div. Nom. iv) that the
natural gifts remain entire in them. Consequently their natural
knowledge was not diminished. The second kind of knowledge, however,
which comes of grace, and consists in speculation, has not been
utterly taken away from them, but lessened; because, of these Divine
secrets only so much is revealed to them as is necessary; and that is
done either by means of the angels, or "through some temporal workings
of Divine power," as Augustine says (De Civ. Dei ix, 21); but not in
the same degree as to the holy angels, to whom many more things are
revealed, and more fully, in the Word Himself. But of the third
knowledge, as likewise of charity, they are utterly deprived.

Reply Obj. 1: Happiness consists in self-application to something
higher. The separate