ntracted through origin; nor is it actual sin,
for it may be altogether without act, as stated above (I-II, Q. 71,
A. 5) when we were treating of sins in general. Therefore omission is
not a special sin.

Obj. 2: Further, every sin is voluntary. Now omission sometimes is
not voluntary but necessary, as when a woman is violated after taking
a vow of virginity, or when one lose that which one is under an
obligation to restore, or when a priest is bound to say Mass, and is
prevented from doing so. Therefore omission is not always a sin.

Obj. 3: Further, it is possible to fix the time when any special sin
begins. But this is not possible in the case of omission, since one
is not altered by not doing a thing, no matter when the omission
occurs, and yet the omission is not always sinful. Therefore omission
is not a special sin.

Obj. 4: Further, every special sin is opposed to a special virtue.
But it is not possible to assign any special virtue to which omission
is opposed, both because the good of any virtue can be omitted, and
because justice to which it would seem more particularly opposed,
always requires an act, even in declining from evil, as stated above
(A. 1, ad 2), while omission may be altogether without act. Therefore
omission is not a special sin.

_On the contrary,_ It is written (James 4:17): "To him . . . who
knoweth to do good and doth it not, to him it is sin."

_I answer that,_ omission signifies the non-fulfilment of a good, not
indeed of any good, but of a good that is due. Now good under the
aspect of due belongs properly to justice; to legal justice, if the
thing due depends on Divine or human law; to special justice, if the
due is something in relation to one's neighbor. Wherefore, in the
same way as justice is a special virtue, as stated above (Q. 58, AA.
6, 7), omission is a special sin distinct from the sins which are
opposed to the other virtues; and just as doing good, which is the
opposite of omitting it, is a special part of justice, distinct from
avoiding evil, to which transgression is opposed, so too is omission
distinct from transgression.

Reply Obj. 2: Omission is not original but actual sin, not as though
it had some act essential to it, but for as much as the negation of
an act is reduced to the genus of act, and in this sense non-action
is a kind of action, as stated above (I-II, Q. 71, A. 6, ad 1).

Reply Obj. 2: Omission, as stated above, is only of such good as is
due and