From the Epistle of the Same Gregory II, to Boniface, A.D. 726

Response I. In the first place it was read in what degree of the stock of relatives marriage is coupled. We say that indeed it was fitting that, so long as they recognize themselves as relatives by affinity, they should not approach the society of this copulation. But because tempering, and especially in so barbarous a nation (namely, the Germans), is more pleasing than the strictness of censure, it must be granted that they be joined after the fourth generation.

Therefore the law of the Roman Church extended the prohibited degrees beyond the fourth; for the law is tempered by dispensation when propinquity is enclosed within the fourth generation.

Response II. For as to what you proposed, namely, if a woman, overcome by infirmity, is unwilling to render the debt to her husband, what should her spouse do? It would be good if he remained thus, that he might devote himself to abstinence. But because this belongs to the great, let him who will not be able to contain himself marry rather; yet let him not withdraw the aid of support from her whom infirmity hinders and no detestable fault excludes.

Cf. Canon XXI of the second Council of Orleans, A.D. 533. When we were writing Thesis XIII (which cf.), it seemed probable to us that this was the decree of Gregory to which Celestine III appeals in the chapter Laudabilem, On the Frigid, because among the genuine epistles of Gregory, whether the second or the third, this one decree alone is extant, to which Celestine seemed not undeservedly to have been able to appeal, and we presumed that the Pontiff had appealed to genuine documents. But because already in collections of canons made before Celestine there occurred a canon under the name of Gregory establishing that same thing more precisely which Celestine decreed (in the decree of Gratian, C. XXVII, q. 2, c. 39; Ivo, p. VII, c. 177; Burchard, L. IX, c. 40), which canon certainly can be genuine, and interpreters judge that Celestine had before his eyes this canon, other than ours, we do not wish to contradict the common opinion.