THE LETTERS OF THE POPES AS SOURCES OF HISTORY.
Cardinal Mai has left recorded his judgment that, "in matter of fact, the whole administration of the Church is learnt in the letters of the Popes".
I draw from this judgment the inference that of all sources for the truths of history none are so precious, instructive, and authoritative as these authentic letters contemporaneous with the persons to whom they are addressed. The first which has been preserved to us is that of Pope St. Clement, the contemporary of St. Peter and St. Paul. It is directed to the Church of Corinth for the purpose of extinguishing a schism which had there broken out. In issuing his decision the Pope appeals to the Three Divine Persons to bear witness that the things which he has written "are written by us through the Holy Spirit," and claims obedience to them from those to whom he sends them as words "spoken by God through us".
If the decisions of the succeeding Popes in the interval of nearly two hundred and fifty years between this letter of St. Clement, about the year 95, and the great letter of St. Julius to the Eusebianising bishops at Antioch in 342, had been preserved entire, the constitution of the Church in that interval would have shone before us in clear light. In fact, we only possess a few fragments of some of these decisions, for there was a great destruction of such documents in the persecution which occupied the first decade of the fourth century. But from the time of Pope Siricius, in the reign of the great Theodosius, a continuous, though not a perfect, series of these letters stretches through the succeeding ages. There is no other such series of documents existing in the world. They throw light upon all matters and persons of which they treat. This is a light proceeding from one who lives in the midst of what he describes, who is at the centre of the greatest system of doctrine and discipline, and legislation grounded upon both, which the world has ever seen. One, also, who speaks not only with a great knowledge, but with an unequalled authority, which, in every case, is like that of no one else, but can even be supreme, when it is directed with such a purpose to the whole Church. Every Pope can speak, as St. Clement, the first of this series, speaks above, claiming obedience to his words as "words spoken by God through us".
In a former volume I made large use of the letters of Popes from Siricius to St. Leo. I have continued that use for the very important period from St. Leo to St. Gregory. Especially in treating of the Acacian schism I have gone to the letters of the Popes who had to deal with it—Simplicius, Felix III., Gelasius, Anastasius II., Symmachus, and Hormisdas. I have done the same for the important reign of Justinian; most of all for the grand pontificate of St. Gregory, which crowns the whole patristic period and sums up its discipline.
I am, therefore, indebted in this volume, first and chiefly, to the letters of the Popes and the letters addressed to them by emperors and bishops, stored up in Mansi's vast collection of Councils (1759, 31 volumes)....