424.  I. IT IS NOT KNOWN WHAT ADULTEROUS LOVE IS, UNLESS IT BE KNOWN WHAT CONJUGIAL LOVE IS.  By adulterous love we mean the love of adultery, which destroys conjugial love, as above, n. 423.  That it is not known what adulterous love is, unless it be known what conjugial love is, needs no demonstration, but only illustration by similitudes:  as for example, who can know what is evil and false, unless he know what is good and true? and who knows what is unchaste, dishonorable, unbecoming, and ugly, unless he knows what is chaste, honorable, becoming, and beautiful? and who can discern the various kinds of insanity, but he that is wise, or that knows what wisdom is? also, who can rightly perceive discordant and grating sounds, but he that is well versed in the doctrine and study of harmonious numbers? in like manner, who can clearly discern what is the quality of adultery, unless he has first clearly discerned what is the quality of marriage? and who can make a just estimate of the filthiness of the pleasures of adulterous love, but he that has first made a just estimate of the purity of conjugial love?  As I have now completed the treatise ON CONJUGIAL LOVE AND ITS CHASTE DELIGHTS, I am enabled, from the intelligence I thence acquired, to describe the pleasures respecting adulterous love.

425.  II.  ADULTEROUS LOVE IS OPPOSED TO CONJUGIAL LOVE.  Every thing in the universe has its opposite; and opposites, in regard to each other, are not relatives, but contraries.  Relatives are what exist between the greatest and the least of the same thing; whereas contraries arise from an opposite in contrariety thereto; and the latter are relatives in regard to each other, as the former are in their regard one to another; wherefore also the relations themselves are opposites.  That all things have their opposites, is evident from light, heat, the times of the world, affections, perceptions, sensations, and several other things.  The opposite of light is darkness; the opposite of heat is cold; of the times of the world the opposites are day and night, summer and winter; of affections the opposites are joys and mourning, also gladnesses and sadnesses; of perceptions the opposites are goods and evils, also truths and falses; and of sensations the opposites are things delightful and things undelightful.  Hence it may be evidently concluded, that conjugial love has its opposite; this opposite is adultery, as every one may see, if he be so disposed, from all the dictates of sound reason.  Tell, if you can, what else is its opposite.  It is an additional evidence in favor of this position, that as sound reason was enabled to see the truth of it by her own light, therefore she has enacted laws, which are called laws of civil justice, in favor of marriages and against adulteries.  That the truth of this position may appear yet more manifest, I may relate what I have very often seen in the spiritual world.  When those who in the natural world have been confirmed