From the Capitular of Gregory II, Given to Martinianus the Bishop and Gregory the Presbyter, Delegates to Bavaria, A.D. 721

Chapter VI. Thus to those marrying or about to marry give order from apostolic authority, that neither because of continence should the nuptial copulation be judged damnable, nor through the license of marrying should an occasion of fornication be presumed ... And it is not lawful to defraud one another except by consent for a time, that they may have leisure for prayer (perhaps something is lacking), the Apostle saying concerning this very thing: You are bound to a wife; do not seek a release, that is, while a spouse survives, not to wish to pass over to the concubitus of another woman ... Whence neither is that rightly to be counted marriage which has exceeded the number of two; because a yoke is not borne except in two. Let that marriage itself also of one man and one wife be taught as not at all to be presumed in nearness of blood: that is, that no one should dare to couple to himself in marriage or associate in adultery the wife of his father, or of his paternal uncle, or of his brother; or his own sister, or the sister of his father or mother, or the daughter of his sister, or even the daughter of the sister of his father or mother. But if anyone has dared to perpetrate this, let him know that he is liable to the contamination of an incestuous crime ... The integrity of faithful virgins and continent persons is also to be taught as preferable to nuptials themselves.