In the primitive Church it was customary for the Holy Eucharist to be celebrated on the anniversary of the death of a martyr--if possible, on his tomb. Where in one diocese there were several martyrs, as, for instance, in that of Caesarea, there were many days in the year on which these commemorations were made, and the Church--say that of Caesarea--drew up a calendar with the days marked on which these festivals occurred. In his "Church History," Eusebius quotes a letter from the Church of Smyrna, in which, after giving an account of the martyrdom of their bishop, S. Polycarp, the disciple of S. John the Divine, the Smyrnians observe: "Our subtle enemy, the devil, did his utmost that we should not take away the body, as many of us anxiously wished. It was suggested that we should desert our crucified Master, and begin to worship Polycarp. Fools! who knew not that we can never desert Christ, who died for the salvation of all men, nor worship any other. Him we adore as the Son of God; but we show respect to the martyrs, as His disciples and followers. The centurion, therefore, caused the body to be burned; we then gathered his bones, more precious than pearls, and more tried than gold, and buried them. In this place, God willing, we will meet, and celebrate with joy and gladness the birthday of this martyr, as well in memory of those who have been crowned before, as by his example to prepare and strengthen others for the combat."[2] S. Polycarp suffered in the year 166; he had been ordained Bishop of Smyrna by S. John in 96. This passage is extremely interesting, for it shows us, in the age following that of the apostles, the Church already keeping the festivals of martyrs, and, as we may conclude from the words of the letter, over the tombs of the martyrs. In this the Church was following the pattern shown to S. John in vision; for he heard the cry of the souls of the martyrs reposing under the altar in heaven. Guided, doubtless, by this, the Church erected altars over the bodies of saints. Among the early Christian writers there are two, S. Paulinus of Nola, and Prudentius, whose testimony is of intrinsic value, not only from its being curiously interesting, but because it is so full and unequivocal as to the fact of the tombs of the martyrs being used as altars.[3] In one of his letters to Severus, S. Paulinus encloses some verses of his own composition, which were to be inscribed over the altar under which was deposited the body of S. Clavus, of whom the venerable prelate says: "Sancta sub aeternis altaribus ossa quiescunt."[4]