Decree of Callistus, Roman Pontiff (A.D. 218-222), from the *Philosophumena*, Book IX, Chapter 12

Since marriages with persons of the lowest rank were prohibited to Roman matrons of a certain more eminent dignity, so that those unions were not reckoned by the law except as concubinage, Callistus, that he might provide for their salvation, conceded that marriages of women of this sort were valid, whomever they had chosen as husband, whether slave or free, although they were not married according to Roman laws. You see here the independent right of the Church putting itself forth.