,
may choose evil, which is to sin through certain malice.

_I answer that,_ The will is related differently to good and to evil.
Because from the very nature of the power, it is inclined to the
rational good, as its proper object; wherefore every sin is said to
be contrary to nature. Hence, if a will be inclined, by its choice,
to some evil, this must be occasioned by something else. Sometimes,
in fact, this is occasioned through some defect in the reason, as
when anyone sins through ignorance; and sometimes this arises through
the impulse of the sensitive appetite, as when anyone sins through
passion. Yet neither of these amounts to a sin through certain
malice; for then alone does anyone sin through certain malice, when
his will is moved to evil of its own accord. This may happen in two
ways. First, through his having a corrupt disposition inclining him
to evil, so that, in respect of that disposition, some evil is, as it
were, suitable and similar to him; and to this thing, by reason of
its suitableness, the will tends, as to something good, because
everything tends, of its own accord, to that which is suitable to it.
Moreover this corrupt disposition is either a habit acquired by
custom, or a sickly condition on the part of the body, as in the case
of a man who is naturally inclined to certain sins, by reason of some
natural corruption in himself. Secondly, the will, of its own accord,
may tend to an evil, through the removal of some obstacle: for
instance, if a man be prevented from sinning, not through sin being
in itself displeasing to him, but through hope of eternal life, or
fear of hell, if hope give place to despair, or fear to presumption,
he will end in sinning through certain malice, being freed from the
bridle, as it were.

It is evident, therefore, that sin committed through certain malice,
always presupposes some inordinateness in man, which, however, is not
always a habit: so that it does not follow of necessity, if a man
sins through certain malice, that he sins through habit.

Reply Obj. 1: To do an action as an unjust man does, may be not only
to do unjust things through certain malice, but also to do them with
pleasure, and without any notable resistance on the part of reason,
and this occurs only in one who has a habit.

Reply Obj. 2: It is true that a man does not fall suddenly into sin
from certain malice, and that something is presupposed; but this
something is not always a habit, as stat