20 And on this account, not, so as it was allowed one man to have even several wives, was it allowed one female to have several husbands, not even for the sake of a family, in case it should happen that the woman could bear, the man could not beget. For by a secret law of nature things that stand chief love to be singular; but what are subject are set under, not only one under one, but, if the system of nature or society allow, even several under one, not without becoming beauty. For neither has one slave so several masters, in the way that several slaves have one master. Thus we read not that any of the holy women served two or more living husbands: but we read that many females served one husband, when the social state of that nation allowed it, and the purpose of the time persuaded to it: for neither is it contrary to the nature of marriage. For several females can conceive from one man: but one female cannot from several, (such is the power of things principal:) as many souls are rightly made subject unto one God. And on this account there is no True God of souls, save One: but one soul by means of many false gods may commit fornication, but not be made fruitful.
Source: On the Good of Marriage (New Advent)