Among the Epistles of the Popes, see Leo IX. epist. 3; Gregor. VII. l. i. epist. 22, 23, l. iii. epist. 19, 20, 21; and the criticisms of Pagi, (tom. iv. A.D. 1053, No. 14, A.D. 1073, No. 13,) who investigates the name and family of the Moorish prince, with whom the proudest of the Roman pontiffs so politely corresponds.