There are two ways of having a concubine which are very different; one is to have a woman to share one's bed with one's wife, and to live at the same time both with her and with the wife. The other is, after a lawful and just separation from a wife, to take another woman to share one's bed.

[2] Those who have a refined and accurate perception of the matter can see that these two ways of having a concubine are as remote from each other as dirty linen is from clean laundry; but those whose perception is muddled and indistinct cannot see this. Those who have conjugial love can see this, those who have a love for adultery cannot. For the latter all that derives from sexual love is dark as night, for the former it is in broad daylight. All the same the adulterous can see what is derived and how to distinguish this, admittedly not in themselves of their own accord, but when they are told by others. Both adulterers and chaste married people are similarly able to raise their intellects; but an adulterer, after learning from others how to make these distinctions, goes on to wipe them from his memory, when he plunges his intellect into his filthy pleasuring. For chastity and unchastity, soundness of mind and folly, cannot exist together, but they can be distinguished by the intellect when it is kept apart.

[3] I once asked some in the spiritual world who had not reckoned adultery to be a sin whether they knew of a single difference between fornication, having a mistress, the two types of concubine, and the various degrees of adultery. They said that one was like another. I asked whether this applied to marriage too. They looked around to see if any clergymen were present, and when they found there were none, said that marriage was in essence similar. It was different with those who had in their thinking reckoned adultery to be a sin. These said that they had seen differences in the inward ideas at the level of perception, but had not so far taken the trouble to distinguish them and tell them apart. I can declare that the angels of heaven perceive even the slightest difference in these. In order therefore to make it plain that there are two mutually opposite ways of having a concubine, one which destroys conjugial love and another which does not, I shall first describe the harmful type and then the harmless one.