that,_ Everything which exists, so far as it exists and
has a particular nature, tends naturally towards some good; since it
comes from a good principle; because the effect always reverts to
its principle. Now a particular good may happen to have some evil
connected with it; thus fire has this evil connected with it that it
consumes other things: but with the universal good no evil can be
connected. If, then, there be anything whose nature is inclined
towards some particular good, it can tend naturally to some evil;
not as evil, but accidentally, as connected with some good. But if
anything of its nature be inclined to good in general, then of its
own nature it cannot be inclined to evil. Now it is manifest that
every intellectual nature is inclined towards good in general, which
it can apprehend and which is the object of the will. Hence, since
the demons are intellectual substances, they can in no wise have a
natural inclination towards any evil whatsoever; consequently they
cannot be naturally evil.

Reply Obj. 1: Augustine rebukes Porphyry for saying that the demons
are naturally deceitful; himself maintaining that they are not
naturally so, but of their own will. Now the reason why Porphyry held
that they are naturally deceitful was that, as he contended, demons
are animals with a sensitive nature. Now the sensitive nature is
inclined towards some particular good, with which evil may be
connected. In this way, then, it can have a natural inclination to
evil; yet only accidentally, inasmuch as evil is connected with good.

Reply Obj. 2: The malice of some men can be called natural, either
because of custom which is a second nature; or on account of the
natural proclivity on the part of the sensitive nature to some
inordinate passion, as some people are said to be naturally wrathful
or lustful; but not on the part of the intellectual nature.

Reply Obj. 3: Brute beasts have a natural inclination in their
sensitive nature towards certain particular goods, with which certain
evils are connected; thus the fox in seeking its food has a natural
inclination to do so with a certain skill coupled with deceit.
Wherefore it is not evil in the fox to be sly, since it is natural to
him; as it is not evil in the dog to be fierce, as Dionysius observes
(De Div. Nom. iv).
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FIFTH ARTICLE [I, Q. 63, Art. 5]

Whether the Devil Was Wicked by the Fault of His Own Will in the
First Instant of His Creation?