“He [i.e. Mamertus] could not abrogate any portion of the right appointed to our brother Leontius by my predecessor of holy memory; since it has been decreed by the law of Christian princes that whatsoever the prelate of the apostolic see may, on his own judgment, have pronounced to churches and their rulers . . . is to be tenaciously observed; nor can those things ever be upset which shall be supported by both ecclesiastical and royal injunction.” Pope St. Hilarius  (Hil. Epp. ix. x. xi. Labbe) (cited by Barmby, J., "Hilarius, bp. of Rome", A Dictionary of Early Christian Biography, (Henry Wace ed.), John Murray and Co., London, 1911)