he lust of
fornication, such as it is in the beginning, is a middle sphere between
the sphere of adulterous love and the sphere of conjugial love, and
makes an equilibrium, n. 455. Care is to be taken, lest by immoderate
and inordinate fornications conjugial love be destroyed, n. 456.
Inasmuch as the conjugial principle of one man with one wife is the
jewel of human life, and the reservoir of the Christian religion, n.
457, 458. With those who, from various reasons, cannot as yet enter into
marriage, and from their passion for the sex, cannot moderate their
lusts, this conjugial principle may be preserved, if the vague love of
the sex be confined to one mistress, n. 459. Keeping a mistress is
preferable to vague amours, provided only one be kept, and she be
neither a maiden nor a married woman, and the love of the mistress be
kept separate from conjugial love, n. 460.

ON CONCUBINAGE, n. 462-476.

There are two kinds of concubinage, which differ exceedingly from each
other, the one conjointly with a wife, the other apart from a wife, n.
463. Concubinage conjointly with a wife, is altogether unlawful for
Christians, and detestable, n. 464. It is polygamy, which has been
condemned, and is to be condemned by the Christian world, n. 465. It is
an adultery whereby the conjugial principle, which is the most precious
jewel of the Christian life, is destroyed, n. 466. Concubinage apart
from a wife, when it is engaged in from causes legitimate, just, and
truly excusatory, is not unlawful, n. 467. The legitimate causes of this
concubinage are the legitimate causes of divorce, while the wife is
nevertheless retained at home, n. 468, 469. The just causes of this
concubinage are the just causes of separation from the bed, n. 470. Of
the excusatory causes of this concubinage some are real and some not, n.
471. The really excusatory causes are such as are grounded in what is
just, n. 472, 473. The excusatory causes which are not real are such as
are not grounded in what is just, although in the appearance of what is
just, n. 474. Those who, from causes legitimate, just, and really
excusatory, are engaged in this concubinage, may at the same time be
principled in conjugial love, n. 475. While this concubinage continues,
actual connection with a wife is not allowable, n. 476.

ON ADULTERIES AND THEIR GENERA AND DEGREES, n. 478-499.

There are three genera of adulteries,--simple, duplicate, and
triplicate, n. 479. Simple adultery is