On 29th June, 1896, Pope Leo XIII issued his Encyclical Letter Satis Cognitum regarding the Unity of the Church to the Patriarchs, Primates, Archbishops, Bishops, and other Ordinaries in Peace and Communion with the Apostolic See:
"14. But if the authority of Peter and his successors is plenary and supreme, it is not to be regarded as the sole authority. For He who made Peter the foundation of the Church also "chose, twelve, whom He called apostles" (Luke vi., 13); and just as it is necessary that the authority of Peter should be perpetuated in the Roman Pontiff, so, by the fact that the bishops succeed the Apostles, they inherit their ordinary power, and thus the episcopal order necessarily belongs to the essential constitution of the Church. Although they do not receive plenary, or universal, or supreme authority, they are not to be looked as vicars of the Roman Pontiffs; because they exercise a power really their own, and are most truly called the ordinary pastors of the peoples over whom they rule."
"But since the successor of Peter is one, and those of the Apostles are many, it is necessary to examine into the relations which exist between him and them according to the divine constitution of the Church. Above all things the need of union between the bishops and the successors of Peter is clear and undeniable. This bond once broken, Christians would be separated and scattered, and would in no wise form one body and one flock. "The safety of the Church depends on the dignity of the chief priest, to whom if an extraordinary and supreme power is not given, there are as many schisms to be expected in the Church as there are priests" (S. Hieronymus, Dialog, contra Luciferianos, n. 9). It is necessary, therefore, to bear this in mind, viz., that nothing was conferred on the apostles apart from Peter, but that several things were conferred upon Peter apart from the Apostles. St. John Chrysostom in explaining the words of Christ asks: "Why, passing over the others, does He speak to Peter about these things?" And he replies unhesitatingly and at once, "Because he was pre eminent among the Apostles, the mouthpiece of the Disciples, and the head of the college" (Hom. lxxxviii. in Joan., n. 1). He alone was designated as the foundation of the Church. To him He gave the power of binding and loosing; to him alone was given the power of feeding. On the other hand, whatever authority and office the Apostles received, they received in conjunction with Peter. "If the divine benignity willed anything to be in common between him and the other princes, whatever He did not deny to the others He gave only through him. So that whereas Peter alone received many things, He conferred nothing on any of the rest without Peter participating in it" (S. Leo M. sermo iv., cap. 2)."