But however it may be with this disputed point of ecclesiastical learning, it suffices Us to be able to state that a commemoration of the supreme pontiff and prayers offered for him during the sacrifice of the Mass is considered, and really is, an affirmative indication which recognizes him as the head of the Church, the vicar of Christ, and the successor of blessed Peter, and is the profession of a mind and will which firmly espouses Catholic unity. This was rightly noticed by Christianus Lupus in his work on the Councils: "This commemoration is the chief and most glorious form of communion" (tome 4, p. 422, Brussels edition). This view is not merely approved by the authority of Ivo of Flaviniaca who writes: "Whosoever does not pronounce the name of the Apostolic one in the canon for whatever reason should realize that he is separated from the communion of the whole world" (Chronicle, p. 228); or by the authority of the famous Alcuin: "It is generally agreed that those who do not for any reason recall the memory of the Apostolic pontiff in the course of the sacred mysteries according to custom are, as the blessed Pelagius teaches, separated from the communion of the entire world" (de Divinis Officiis, bk. 1, chap. 12).

Pope Pelagius II who held the Apostolic See in the sixth century of the Church gives this weightier statement on Our present subject in his letter: "I am greatly astonished at your separation from the rest of the Church and I cannot equably endure it. For Augustine, mindful that the Lord established the foundation of the Church on the Apostolic sees, says that whosoever removes himself from the authority and communion of the prelates of those sees is in schism. He states plainly that there is no church apart from one which is firmly established on the pontifical bases of the Apostolic sees. Thus how can you believe that you are not separated from the communion of the whole world if you do not commemorate my name during the sacred mysteries, according to custom? For you see that the strength of the Apostolic See resides in me, despite my unworthiness, through episcopal succession at the present time" (Labbe, Conciliorum Collectione, vol. 5, col. 794f and 810). This letter of Pelagius has also been used by St. Agobard, the great archbishop of Lyons, in his treatise De comparatione utriusque regiminis. This is printed in the in Magna Bibliotheca Patrum (vol. 14, p. 315, no. 21, Lyons) and was reissued by Balutius with other writings of this saint (col. 2, p. 49).