In the first centuries of the Church, not only the Saints whose bodies reposed in the church, but also the dead of the congregation were commemorated.

When a Roman Consul was elected, on entering on his office he distributed among his friends certain presents, called diptychs. These diptychs were folding tablets of ivory or boxwood, sometimes of silver, connected together by hinges, so that they could be shut or opened like a book. The exterior surface was richly carved, and generally bore a portrait of the Consul who gave them away. Upon the inner surface was written an epistle which accompanied the present, or a panegyric on himself. They were reminders to friends, given much as a Christmas card is now sent. The diptych speedily came into use in the Church. As the Consul on his elevation sent one to his friends to remind them of his exaltation, so, on a death in the congregation, a diptych was sent to the priest as a reminder of the dead who desired the prayers of the faithful. At first, no doubt, there was a pack of these little memorials, each bearing the name of the person who desired to be remembered at the altar. But, for convenience, one double tablet was after a while employed instead of a number, and all the names of those who were to be commemorated were written in this book. From the ancient liturgies we gather that it was the office of the deacon to rehearse aloud, to the people and the priest, this catalogue registered in the public diptychs. In the "Ecclesiastical Hierarchy," attributed to S. Dionysius the Areopagite, but really of a later date, the end of the fifth century, the author says of the ceremonies of the Eucharist, that after the kiss of peace, "When all have reciprocally saluted one another, there is made the mystic recitation of the sacred tablets."[7] In the Liturgy of S. Mark we have this, "The deacon reads the diptychs (or catalogue) of the dead. The priest then bowing down prays: To the souls of all these, O Sovereign Lord our God, grant repose in Thy holy tabernacle, in Thy kingdom, bestowing on them the good things promised and prepared by Thee," etc.

It is obvious that after a while the number of names continually swelling would become too great to be recited at once. It became necessary, therefore, to take some names on one day, others on another. And this originated the Necrologium, or catalogue of the dead. The custom of reading the diptychs has ceased to be observed in the Roman Liturgy, though we find it indicated there by the "Oratio supra Diptycha." At present, when the celebrating priest arrives at that part of the Canon called the "Memento," he secretly commemorates those for whose souls he more particularly wishes to pray.

But, in addition to the diptychs of those for whom the priest and congregation were desired to pray, there was the catalogue of the Martyrs and Saints for whom the Church thanked God. For instance, in the modern Roman Mass, in the Canon we have this commemoration: "Joining in communion with, and reverencing, in the first place, the memory of the glorious and ever-virgin Mary, Mother of our God and Lord Jesus Christ; as also of Thy blessed apostles and martyrs, Peter and Paul, Andrew, James, John, Thomas, James, Philip, Bartholomew, Matthew, Simon and Thaddæus; Linus, Cletus, Clement, Xystus, Cornelius, Cyprian, Laurence, Chrysogonus, John and Paul, Cosmas and Damian, and of all Thy Saints," etc. This is obviously a mere fragment of a commemoration of the Blessed Virgin, of the apostles, and then of the special Roman martyrs. The catalogue of the Saints to be remembered was long; there were hundreds of martyrs at Rome alone, and their names were written down on sacred diptychs especially appropriated to this purpose. Such an inscription was equivalent to the present ceremony of canonization. The term canonization itself tells the history of the process. It is derived from that part of the Mass called the Canon, in which occurs that memorial already quoted. On the day when the Pope, after a scrutinizing examination into the sanctity of a servant of God, formally inscribes him among the Saints, he adds his name at the end of those already enumerated in the Canon, after "Cosmas and Damian," and immediately reads Mass, adding this name at this place. Formerly every bishop could and did canonize—that is, add the name of any local Saint or martyr worthy of commemoration in his diocese.

When the list became long, it was found impracticable to commemorate all nominatim at once, and the Saints were named on their special days. Thus, out of one set of diptychs grew the Necrologium, and out of the other the Martyrology.

The Church took pains to collect and commit to writing the acts of the martyrs. This is not to be wondered at; for the martyrs are the heroes of Christianity, and as the world has her historians to record the achievements of the warriors who have gained renown in conflict for power, so the Church had her officers to record the victories that her sons won over the world and Satan. The Saints are the elect children of the spouse of Christ, the precious fruit of her body; they are her crown of glory. And when these dear children quit her to reap their eternal reward, the mother retains precious memorials of them, and holds up their example to her other children to encourage them to follow their glorious traces.

The first to institute an order of scribes to take down the acts of the martyrs was S. Clement, the disciple of S. Peter, as we are told by Pope S. Damasus, in the "Liber Pontificale."[8] According to this tradition, S. Clement appointed seven notaries, men of approved character and learning, to collect in the city of Rome, each in his own region of the city, the acts of the martyrs who suffered in it. To add to the guarantee of good faith, Pope S. Fabian[9] placed these seven notaries under the control of the seven subdeacons, who with the seven deacons were placed over the fourteen cardinal regions of the city of Rome. Moreover, the Roman Pontiffs obtained the acts of martyrs who had suffered in other churches. These acts were the procès verbal of their trial, with the names of the judges under whom they were sentenced, and an account of the death endured. The acts of S. Philip of Heraclea, SS. Hilary and Tatian, and SS. Peter, Paul, Andrew, and Dionysia, are examples of such acts. Other acts were those written by eye-witnesses, sometimes friends of the martyrs; those of the martyrs, SS. Perpetua, Felicitas, and their companions are instances. The first part of these was written by S. Perpetua herself, and reaches to the eve of her martyrdom; then another confessor in the same prison took the pen and added to the eve of his death, and the whole was concluded by an eye-witness of their passion. Other acts again were written by those who, if not eye-witnesses, were able, from being contemporaries and on the spot, to gather reliable information; such are the narratives of the martyrs of Palestine by Eusebius, Bishop of Cæsarea. Unfortunately, comparatively few of the acts of the martyrs have come down to us in their genuine freshness; and the Church of Rome, which set the example in appointing notaries to record the facts, has been most careless about preserving these records unadulterated; so that even the acts of some of her own bishops and martyrs, S. Alexander, and S. Marcellinus, and S. Callixtus, are romances devoid of all stamp of truth.

Tertullian[10] says that on the natal days, that is, on the days of martyrdom of the Saints who have suffered for Christ, "We keep an annual commemoration." It is easy to see how this usage necessitated the drawing up of lists in which were inscribed not only the names of the martyrs, and the place of their decease, but also a few words relative to their conflict, so that the people might associate their names with their victories, and the names might not become, in time, to them empty sounds. S. Cyprian was absent from Carthage when the persecution was raging there, but he wrote to his clergy, "Note the days of their death, that we may celebrate their commemorations along with the memorials of the martyrs."[11] S. Augustine says,[12] "The Christian people celebrate the memory of the martyrs with religious solemnity, both to excite to imitation, and that they may become fellows in their merits and be assisted by their prayers."

Adrian I. quotes the 13th Canon of the African Church and the 47th of the third Carthaginian Council, in a letter to Charlemagne, in which he says, "The Sacred Canons approved of the passions of the Holy Martyrs being read in Church when their anniversary days were being celebrated."