There cannot exist anything in the universe which does not have its opposite. Opposites are not differentiated as relative, but as contrary. Relative differences are between the greatest and least of the same thing, but contraries are direct opposites. Contraries have relative differences between them, just as their opposites have. So their relationships themselves too are opposite.

It is obvious that every single thing has its opposite, from a consideration of light, heat, times and seasons, affections, perceptions, sensations and many more things. The opposite of light is darkness, of heat cold; the opposites in times and seasons are day and night, summer and winter. The opposites in affection are joy and grief, gladness and sadness. The opposites in perceptions are good and evil, truths and falsities. The opposites in sensations are pleasure and distress.

All the evidence from these comparisons allows the conclusion that conjugial love too has its opposite, and anyone can, if he wishes, see that all the dictates of sound reason assert that this is adultery. Tell me, if you can, what other opposite it has. Moreover since this is plainly to be seen by the light of sound reason, it has been established by the laws of what is called civil justice that marriage is to be encouraged and adultery discouraged.

[2] To make it even plainer that these are opposites, I may report something I have many times witnessed in the spiritual world. Those who in the natural world have been confirmed adulterers, on perceiving the sphere of conjugial love coming down from heaven, immediately either run away and hide in caverns or, if they hold out against it, become furiously angry and rage like furies. The reason this happens is that all the pleasant and unpleasant effects of affections are perceived there, sometimes as clearly as a smell is perceived by the nose, for there is no material body to absorb such things.

[3] However, the reason for the opposition of scortatory and conjugial love being unknown to many in the natural world is the pleasures of the flesh, which appear to imitate the pleasures of conjugial love at the outermost level, so that those who merely feel pleasure know nothing of this opposition. I could hazard the opinion that, if you asserted that everything has its opposite, and that therefore conjugial love must have its opposite, adulterers would reply that there is no opposite to this love, since there is no way scortatory love can be distinguished from it.

It is also obvious from this that anyone ignorant of the nature of conjugial love is also ignorant of the nature of scortatory love. Moreover, it is not possible to know the nature of conjugial love from a consideration of scortatory love, but it is possible to know scortatory love from a consideration of conjugial love. No one knows good from a consideration of evil, but evil from a consideration of good. For evil is in thick darkness, but good in light.