Man is born into a love of evil and falsity, which love is the love of
adultery; and this love cannot be turned about and changed into
spiritual love, which is an image of God, and still less into celestial
love, which is a likeness of God, except by a marriage of good and truth
from the Lord, and not fully except by a marriage of two minds and two
bodies. From this it is clear why marriages are heavenly and adulteries
infernal; for marriage is an image of heaven, and true marriage love is
an image of the Lord, while adultery is an image of hell, and love of
adultery is an image of the devil. Moreover, marriage love appears in
the spiritual world in form like an angel, and love of adultery in form
like a devil. Reader, treasure this up within you, and after death,
when you are living as a spirit-man, inquire whether this is true, and
you will see. (A.E., n. 984.)

How profane and thus how much to be detested adulteries are can be seen
from the holiness of marriages. All things in the human body, from the
head to the sole of the feet, both interior and exterior, correspond to
the heavens, and in consequence man is a heaven in its least form, and
also angels and spirits are in form perfectly human, for they are forms
of heaven. All the members devoted to generation in both sexes,
especially the womb, correspond to societies of the third or inmost
heaven, and for the reason that true marriage love is derived from the
Lord's love for the church, and from the love of good and truth which is
the love of the angels of the third heaven; therefore marriage love,
which descends therefrom as the love of that heaven, is innocence, which
is the very being (esse) of every good in the heavens. And for this
reason embryos in the womb are in a state of peace, and when they have
been born as infants are in a state of innocence; so, too, is the mother
in relation to them.