ue
matter, other due circumstances are not observed. And since a
circumstance, as such, does not specify a moral act, whose species is
derived from its object which is also its matter, it follows that the
species of lust must be assigned with respect to its matter or object.

Now this same matter may be discordant with right reason in two ways.
First, because it is inconsistent with the end of the venereal act.
In this way, as hindering the begetting of children, there is the
_vice against nature,_ which attaches to every venereal act from
which generation cannot follow; and, as hindering the due upbringing
and advancement of the child when born, there is _simple
fornication,_ which is the union of an unmarried man with an
unmarried woman. Secondly, the matter wherein the venereal act is
consummated may be discordant with right reason in relation to other
persons; and this in two ways. First, with regard to the woman, with
whom a man has connection, by reason of due honor not being paid to
her; and thus there is _incest,_ which consists in the misuse of a
woman who is related by consanguinity or affinity. Secondly, with
regard to the person under whose authority the woman is placed: and
if she be under the authority of a husband, it is _adultery,_ if
under the authority of her father, it is _seduction,_ in the absence
of violence, and _rape_ if violence be employed.

These species are differentiated on the part of the woman rather than
of the man, because in the venereal act the woman is passive and is
by way of matter, whereas the man is by way of agent; and it has been
stated above (Obj. 1) that the aforesaid species are assigned with
regard to a difference of matter.

Reply Obj. 1: The aforesaid diversity of matter is connected with a
formal difference of object, which difference results from different
modes of opposition to right reason, as stated above.

Reply Obj. 2: As stated above (I-II, Q. 18, A. 7), nothing hinders
the deformities of different vices concurring in the one act, and in
this way adultery is comprised under lust and injustice. Nor is this
deformity of injustice altogether accidental to lust: since the lust
that obeys concupiscence so far as to lead to injustice, is thereby
shown to be more grievous.

Reply Obj. 3: Since a woman, by vowing continence, contracts a
spiritual marriage with God, the sacrilege that is committed in the
violation of such a woman is a spiritual adultery. In like manne