Concerning concubinage (1849-1872 [CL 462-476]). Concubinage is the adjunction of a concubine to a wife (1851 [CL 462]).

The adjunction of a concubine to a wife, or simultaneous concubinage, is altogether unlawful to Christians, and is detestable (1852-1857 [CL 464]). It is polygamy, which has been condemned in the Christian world, and is to be condemned (1858, 1859 [CL 465]).

It is whoredom, by which the conjugial, which is the jewel of Christian life, is destroyed (n. 1860-1862 [CL 466]).

There are two kinds of concubinage, which differ very greatly from each other: one kind is simultaneous, or conjointly with a wife; the other is substitutional, and is apart from a wife; and there are causes legitimate, just and excusatory, which concede this second kind of concubinage (1863 [CL 463, 467]).

Legitimate causes which concede concubinage that is substitutional and apart from the wife, are the legitimate causes of divorce (1864-1866 [CL 468, 469]).

Just causes are all the just causes of separation as to bed (1867 [CL 470]).

The excusatory causes are real and are not real. Excusatory causes that are real, are those which are drawn from what is just; excusatory causes which are not real, are those which are not drawn from what is just, although from an appearance of it (1868, 1869 [CL 471-474]).

The love of concubinage and conjugial love are diverse (1870 [CL 466]).