on 1: It would seem that there can be no evil of fault in the
angels. For there can be no evil except in things which are in
potentiality, as is said by the Philosopher (Metaph. ix, text. 19),
because the subject of privation is a being in potentiality. But the
angels have not being in potentiality, since they are subsisting
forms. Therefore there can be no evil in them.

Obj. 2: Further, the angels are higher than the heavenly bodies. But
philosophers say that there cannot be evil in the heavenly bodies.
Therefore neither can there be in the angels.

Obj. 3: Further, what is natural to a thing is always in it. But it
is natural for the angels to be moved by the movement of love towards
God. Therefore such love cannot be withdrawn from them. But in loving
God they do not sin. Consequently the angels cannot sin.

Obj. 4: Further, desire is only of what is good or apparently good.
Now for the angels there can be no apparent good which is not a true
good; because in them either there can be no error at all, or at
least not before guilt. Therefore the angels can desire only what it
truly good. But no one sins by desiring what is truly good.
Consequently the angel does not sin by desire.

_On the contrary,_ It is said (Job 4:18): "In His angels He found
wickedness."

_I answer that,_ An angel or any other rational creature considered in
his own nature, can sin; and to whatever creature it belongs not to
sin, such creature has it as a gift of grace, and not from the
condition of nature. The reason of this is, because sinning is nothing
else than a deviation from that rectitude which an act ought to have;
whether we speak of sin in nature, art, or morals. That act alone, the
rule of which is the very virtue of the agent, can never fall short of
rectitude. Were the craftsman's hand the rule itself engraving, he
could not engrave the wood otherwise than rightly; but if the
rightness of engraving be judged by another rule, then the engraving
may be right or faulty. Now the Divine will is the sole rule of God's
act, because it is not referred to any higher end. But every created
will has rectitude of act so far only as it is regulated according to
the Divine will, to which the last end is to be referred: as every
desire of a subordinate ought to be regulated by the will of his
superior; for instance, the soldier's will, according to the will of
his commanding officer. Thus only in the Divine will can there be no
sin; whereas