From the Epistle of Gregory VII, to the Bishops of Asti, Turin, and Acqui, A.D. 1079

It has come to us that Boniface, marquis, brother of Manfred and Anselm, recently killed, is attempting to couple to himself in marriage the betrothed of the same Anselm. No one who knows the sacred canons can doubt how full of disgrace this is, how alien from the laws of the Christian religion.

Civil law had established or advised the impediment of public honesty from espousals. Institutes, Book I, Title X, §9: "It is established that neither is the son's betrothed a daughter-in-law, nor the father's betrothed a stepmother; nevertheless those who have abstained from nuptials of this sort will act more rightly and lawfully." The Church received and amplified this impediment. Therefore Gregory cites the sacred canons. Yet this impediment from espousals a certain Pope Benedict did not acknowledge, whose response is brought forward in the Collection of Canons, which is an Appendix to the Third Lateran Council (see below), if nevertheless that response is authentic.