Rabanus Maurus : The letters themselves are written in the name of the king and then sealed with his ring, because the teaching of the Gospels—which are preached throughout the world in the name of Christ—are declared everywhere to be confirmed by the seal of the Holy Spirit, since the preachers themselves, who are filled with its gift, seem to everyone to be undefeatable in their unflagging strength and to remain ever glorious and triumphant over their enemies. — Commentary on Esther