With this century the great persecutions begin. That of Septimius Severus arose in the year 202. Now a persecution which assaulted the mass of Christians was the occasion of fall and apostasy to some, of martyrdom to others. Hence the question became urgent how those should be treated by the Christian society who through fear of suffering had failed to maintain the confession of their faith. It was necessary to lay down more distinctly rules as to what crimes should be admitted to penance, and what that penance should be. The practice here involved doctrine; it raised immediately the question of the power which the society itself had to grant pardon, and to receive the guilty back into its bosom. And here the authority of the chief Bishop was at once called out. We find as a matter of fact Pope Zephyrinus in the first years of this century determining the rules of penance, and a small party of rigid disciplinarians, among whom Tertullian was conspicuous, who considered his rules as too indulgent. It is in the vehement pamphlet with which Tertullian assails the Pope that we have one of the earliest expressions of the great authority claimed by him. “I hear,” he exclaims, “that an edict has been set forth, and a peremptory one. The Pontifex Maximus, in sooth, that is, the Bishop of Bishops, issues his edict: I pardon to those who have discharged their penance the sins both of adultery and of fornication.”(296) Twenty years later Pope Callistus carried the indulgence yet further, receiving to penance those who had committed murder or idolatry.(297) Once more, after a period of thirty years, the breaking out of the Decian persecution raised afresh the question of admitting great sinners to penance, and the actual discipline of the Roman Church, as established under Zephyrinus and Callistus, is set forth in a letter to Cyprian by Novatian, then one of the most esteemed presbyters of that church. By the discipline which these facts attest it is determined that the Church has lodged in her the power of pardoning any sin whatsoever according to the rules of the penance which she imposes. And it is the Roman Church which herein takes the guidance. She maintained the ancient faith, severity, and discipline, yet tempered with that consideration which the full possession of the truth alone bestows.(298) Thus she received back without hesitation those who returned from heresy or schism, as well as those who had fallen in the conflict with persecution.