From the Council of Toledo, A.D. 527 or 531

Canon I. Concerning those whom the will of their parents has bound from the first years of infancy to the office of clericate, we establish that this is to be observed: that as soon as they have been tonsured or handed over to the ministry of readers, they ought to be educated in the house of the Church, under episcopal presence, by one placed over them. But when they have completed the eighteenth year of their age, their will concerning seeking marriage is to be examined by the bishop before the sight of the whole clergy and people. If, with God inspiring, the grace of chastity has pleased them, and they have promised that they will preserve the profession of their chastity without conjugal necessity, these, as seekers of the narrowest life, are to be subjected to the most gentle yoke of the Lord, and first, the proof of their profession having been had, they are to receive the ministry of the subdiaconate from the twentieth year ... Yet they must beware lest at any time, forgetful of their promise, they run either to earthly nuptials or to furtive concubitus. But if perhaps they have done this, let them be condemned as guilty of sacrilege and be held strangers from the Church. But to those whom their own will, at the time of the interrogation, has persuaded to the desire of marrying, we cannot take away the license conceded by the Apostles, in such a way that when, placed in marriage at a more advanced age, they have promised by equal consent that they will renounce the works of the flesh, they may aspire to sacred orders.

Cf. Canon XLIX of the fourth Council of Toledo below, A.D. 633.

Canon IV. Let no one of the faithful desire to be coupled to a blood-relative of his own, so far as he knows the lineaments of affinity by succession of kind, in marriage ... and let him be separated by a so much longer time of excommunication from the body of Christ and the fellowship of brotherhood, as he has been polluted by the contagion of nearer blood.

Here indeed there is not presented a distinct enumeration of the degrees of consanguinity or affinity between which it is not lawful to enter marriage; yet the formula of speaking is so general that of itself it comprehends all degrees of propinquity which are wont to be reckoned among men. Yet that the Spaniards had established some limit below which it would not be lawful to enter marriages is not permitted to be doubted by the series of generations which shortly afterward flourished in Spain, Isidore of Seville, who brings consanguinity down to the sixth generation (see below under Gregory the Great). But by a certain limit, received from the common mode of reckoning, that general formula of the Fathers of Toledo, as also of the Fathers of Agde (cf. above), was putting on a determinate sense. Cf. what we shall say after Gregory the Great.

Likewise observe that this formula: "so far as he knows the lineaments of affinity by succession of kind" can comprehend not only consanguinity, but also affinity properly so called, and that manifoldly.