Ordinary licentiousness or simple adultery does not involve a love analogous to conjugial love, for it is only an urge of the flesh which immediately subsides, and which sometimes leaves behind it not a trace of any love for the woman. Consequently, if this boiling over of lasciviousness is not purposeful or deliberate, and if the adulterer repents of it, it takes away only a little something from conjugial love. It is otherwise with polygamous licentiousness. It does involve a love analogous to conjugial love; for it does not subside, fade, and disappear after boiling over as the former does, but remains, grows and ensconces itself, and in the same measure it takes away from love for the wife and induces a coldness toward her instead. Indeed, the man then regards the harlot who shares his bed as lovable because of the freedom of will he has in being able to withdraw if he chooses - a trait that is inborn in the natural self and which, because it is therefore pleasing, supports that love. And furthermore, with all its allurements he has with the mistress a closer union than with his wife. On the other hand, he does not regard his wife as lovable because of the obligation he has of living with her, an obligation enjoined on him by a covenant for life, which he then perceives as all the more compelled because of the freedom he has with the other. It follows that love for the married partner cools in the same degree that love for the adulterous one grows warmer, and that the first is despised in the measure that the latter is prized. [2] With respect to the second point, it can be seen that taking a mistress simultaneously or conjointly with the wife robs a man of every capacity for and inclination to married life which is present in Christians from birth, from the following considerations:

In the measure that love for the married partner is transferred to love for a mistress, in the same measure it is taken away, depleted and dissipated with respect to the married partner, as shown just above. This comes about as a result of the closing of the interior elements of the man's natural mind and the opening of its lower ones, as may be seen from considering that the seat of the inclination in Christians to love one of the opposite sex is in the inmost elements of a person, and from the fact that this seat can be closed off, although not eradicated. An inclination to love one of the opposite sex, and with it a capacity for receiving that love, has been implanted in Christians from birth, for the reason that this love comes from the Lord alone and has been made part of their religion, and because in Christianity the Lord's Divinity is acknowledged and worshiped, and religion is derived from His Word. Hence the implantation of that inclination, and also its transmission from generation to generation. We said that this Christian conjugial inclination is lost by polygamous licentiousness, but what we mean is that it is closed up and cut off in the Christian polygamist. However, it may still be reawakened in his descendants, as happens in the instance of the likeness of a grandfather or great grandfather reappearing in a grandson or great grandson. That is why we call this conjugial inclination the precious treasure of Christian life, and above in nos. 457, 458, the precious jewel of human life and the repository of Christian religion. [3] It is clearly apparent that by polygamous licentiousness this conjugial inclination is lost in a Christian who engages in it, from the fact that it is impossible for him to love a mistress and a wife equally in the way that a polygamous Muslim can. Rather, the more he loves the mistress, the less he loves his wife, or the warmer he grows toward the first, the colder he becomes to the latter. Moreover, what is even more despicable, in the same measure, too, he at heart accepts the Lord only as a natural man and Mary's son, and not at the same time the Son of God, and to that extent also attaches little importance to religion. It should be properly recognized, however, that this is what happens in the case of those who take a mistress in addition to the wife and engage in a physical union with both; and not at all in the case of those who for legitimate, just and truly weighty reasons separate and disunite themselves from the wife in respect to physical love, substituting another woman in her stead. Consideration of the latter kind of circumstance in taking a mistress now follows.