Dei Gratia (Lat. by the grace of God) is a formula used by bishops and monarchs. "Felix of Rome (A.D. 356) styled himself episcopus per Dei gratiam. Afterwards it came to be appended by archbishops, bishops, abbots, abbesses, deans, monks, and even chaplains, to their titles in letters and other documents, as an expression of dependence. After the middle of the 13th century, when the sanction of the pope began to be considered necessary to ecclesiastical offices, the higher clergy wrote Dei et Apostolicae sedis gratis, 'by the favor of God and the apostolic see.' At a later period many of them preferred to write miseratione divin, permissione divina, and the like; but they still continued to be styled by others Dei gratia. In the British Islands this style was generally dropped about the time of the Reformation, but it was occasionally given to the archbishops of Canterbury and York even after the beginning of the 17th century. Beginning with the times of the Carlovingians, many temporal princes, earls, and barons made use of the formula Dei Gratia; and before the 15th century no idea of independence or of divine right seems to have attached to it. But in 1442, king Charles VII of France forbade its use by the Comte d'Armagnac, and in 1449 obliged the duke of Burgundy to declare that he used it without prejudice to the rights of the French crown. These instances show that it had now begun to be regarded as belonging exclusively to sovereigns who owed no allegiance to any other earthly potentate or power. In this way, what was originally a pious expression of humility came to be looked upon as an assertion of the doctrine of the 'divine right' of kings."