in its acts is impurity itself and unchastity itself. Since the
delights of these two loves are alike in outward appearance, although
inwardly they are wholly unlike, because opposites, the Lord provides
that the delights of adultery shall not ascend into heaven and that the
delight of marriage shall not descend into hell; and yet that there
shall be some correspondence of heaven with prolification in adulteries,
though none with the delight itself in them. (A.E., n. 990.)

It has been said that marriage love, which is natural, descends from the
love of good and truth, which is spiritual; this spiritual therefore is
in the natural love of marriage as a cause is in its effect. So from
the marriage of good and truth there comes forth a love of bearing
fruit, that is, good through truth and truth from the good; and from
that love a love of producing offspring descends, and in that love there
is every delight and pleasure.

On the contrary, love of adultery, which is natural, springs from a love
of evil and falsity, which is spiritual; consequently this spiritual is
in the natural love of adultery as a cause is in its effect. So from
the marriage of evil and falsity by love there comes forth a love of
bearing fruit, namely, evil through falsity and falsity from evil; and
from that love a love of producing offspring in adulteries descends, and
in that love there is every delight and pleasure.

There is every delight and pleasure in the love of producing offspring,
because all that is delightful, pleasurable, blessed, and happy, in the
whole heaven and in the whole world, has been from creation brought
together into the effort and thus into the act of bringing forth uses;
and these joys increase in an ascending degree to eternity, according to
the goodness and excellence of the uses. This make evident why the