Question IV

GRATIAN. It is now asked why union within consanguinity is prohibited down to the sixth degree. Isidore writes about these matters as follows in book XI of the Etymologies, c. 6:

When consanguinity, gradually separating itself through the orders of its lines of descent, has withdrawn itself down to the last degree and has ceased to be relationship, then for the first time the law will receive it into the bond of marriage and will, as it were, call back what is fleeing. Consanguinity was established down to the sixth degree of lineage for this reason: so that, just as the generation and condition of the human being is ended in the six ages of the world, so the relationship of lineage may be terminated in as many degrees.