It will first of all have to be established by Your Majesty which persons he wishes to be joined in marriage. The law of God and of the emperors forbids marriage only to those who are related in the ascendant and descendant line, and collaterally to paternal and maternal aunt, to sister, sister’s daughter and granddaughter, to brother’s daughter, likewise by affinity to stepdaughter, stepmother, daughter-in-law, mother-in-law, brother’s wife, father’s wife, to wife’s daughter and granddaughter (Lev. 18:7-18); certain laws of emperors add brother’s and sister’s grandchildren. They also forbid marriage to those who are too disparate in condition of life, so that a plebeian may not marry the daughter of a senator, or a senator a plebeian, nor a free person a slave. They also forbid marriages to adopted daughters and godchildren, of a tutor to his pupil, or that a provincial governor or his son takes a wife from among his subjects. The law of both God and the emperors permits marriage to cousins, whether they are so related through two sisters, or brother and sister, i.e., whether they have this relationship on the father’s brother’s or sister’s side, or are cousins properly so called. For although at the time of Augustine, as he recalls in the sixteenth chapter of the fifteenth book of The City of God, marriages of cousins were forbidden by law, nevertheless that law was at once revoked, as is clear in the law of Arcadius and Honorius, and in the Institutes of Justinian.
Certain Roman pontiffs forbade the marriage of relatives to the seventh generation. Afterward they reduced this prohibition to the fourth generation. But Gregory I allowed the Angles to marry in the fourth degree of kindred and forbade them in the second, i.e., with cousins, but he gives a rather shallow reason for his prohibition. For he writes that he has learned from experience that offspring cannot come from such a marriage.
Saint Augustine in the passage just cited gives two reasons why it is suitable for Christians not to take spouses from among their own relatives: first, that by affinity with outsiders, charity among men and interdependence are the more expanded; secondly, that “there is something natural and laudable in human modesty which keeps one from a union with a woman to whom respect is due because of consanguinity; the union may be for propagation, but is nevertheless lustful, one which we see even conjugal modesty blushing over.”
Further, we read that the ancient holy fathers, Abraham, Isaac, and others, preferred to unite their children with relatives of whose character and pious education they had more knowledge (Gen. 20:12; 24:40; 29:10-28). And this, certainly, must be looked for in arranging a marriage that those involved be in proper accord in regard to religion and ways of life, which can be determined more easily among friends and relatives than among Strangers.
Moreover, unless the love of Christ, which disregards blood relationship, arouses and preserves the love between relatives, we observe that relationships between one’s relatives and outsiders very often cause contention, hatred, and sometimes even wars, rather than that they prove to be the means of a broader goodwill and love. For whatever property is transferred by matrimony to relatives by marriage, blood relatives who are not moved by the Spirit of Christ think that it has been wrongfully snatched from their own grasp.
On this account, I myself am of the opinion that it is fitting for pious princes and governors of states, in defining the degrees of consanguinity and affinity pertinent to the association of marriage, to follow the laws of God and the examples of the holy patriarchs praised in Holy Scriptures, rather than what men have later invented and observed in this matter, especially since pious emperors also preferred in their laws to follow the divine arrangement rather than human judgment.
I confess that we being free in Christ are not bound by the civil laws of Moses any more than by the ceremonial laws given to ancient Israel, insofar as they pertain to external circumstances and elements of the world; nevertheless, since there can be no laws more honorable, righteous, and wholesome than those which God himself, who is eternal wisdom and goodness, enacted, if only they are applied under God’s judgment to our own affairs and activities, I do not see why Christians, in matters which pertain also to their own doings, should not follow the laws of God more than those of any men. We have no need to observe circumcision, sacrifices, multiple purifications of the body and of outward practices which the Lord especially commanded to the Jews through Moses; but from the things which the Lord commanded concerning such matters, we rightly and devoutly learn with what reverence we ought to administer holy Baptism and the Eucharist, and to receive them as well, and what great purity and chastity we ought to observe in the use of all things corporal. How much more, therefore, must we diligently observe what the Lord commanded and taught by the examples he gave concerning holy marriage. We use it no less than the ancients by God’s institution.
This is what I have to say about persons who may fittingly be joined in matrimony.
