468. (vi) The lawful reasons for having a concubine of this kind are those which are lawful grounds for divorce, when the wife is none the less kept at home.
Divorce means the abolition of the marriage compact leading to full separation, and followed by the freedom to marry another wife. The sole reason for this total separation or divorce is promiscuity as laid down by the Lord (Matt. 19:9). Included under the same heading are cases of obvious obscenity which ruin modesty and fill the house with criminal pandering, making it uncomfortable to live in; this gives rise to the shamelessness of a prostitute, the result of a totally dissolute mind. To this may be added malicious desertion involving promiscuity, which causes a wife to become promiscuous and so to be rejected (Matt. 5:32). These three reasons, being lawful grounds for divorce, the first and third before a judge and the second in the husband's own judgment, are lawful reasons for taking a concubine, but only when the wife is kept on at home. Promiscuity is the sole reason for divorce, because it is the diametrical opposite of the life of conjugial love, being so pernicious as to murder it (see 255 above).