Callistus, who was made bishop on the death of Zephyrinus, must have possessed a far more vigorous intellect than his predecessor.  Though regarded by the orthodox Hippolytus with no friendly eye, it is plain that he was endowed with an extraordinary share of energy and perseverance.  He had been originally a slave, and he must have won the confidence of his wealthy Christian master Carpophores, for he had been intrusted by him with the care of a savings bank.  The establishment became insolvent, in consequence, as Hippolytus alleges, of the mismanagement of its conductor; and many widows and others who had committed their money to his keeping, lost their deposits.  When Carpophorus, by whom he was now suspected of embezzlement, determined to call him to account, Callistus fled to Portus—­in the hope of escaping by sea to some other country.  He was, however, overtaken, and, after an ineffectual attempt to drown himself, was arrested, and thrown into prison.  His master, who was placable and kind-hearted, speedily consented to release him from confinement; but he was no sooner at large, than, under pretence of collecting debts due to the savings bank, he went into a Jewish synagogue during the time of public worship, and caused such disturbance that he was seized and dragged before the city prefect.  The magistrate ordered him first to be scourged, and then to be transported to the mines of Sardinia.  He does not appear to have remained long in exile; for, about this time, Marcia procured from the Emperor Commodus an order for the release of the Christians who had been banished to that unhealthy island; and Callistus, though not included in the act of grace, contrived to prevail upon the governor to set him at liberty along with the other prisoners.  He now returned to Rome, where he appears to have acquired the reputation of a changed character.  In due time he procured an appointment to one of the lower ecclesiastical offices; and as he possessed much talent, he did not find it difficult to obtain promotion.  When Zephyrinus was advanced to the episcopate, Callistus, who was his special favourite, became one of the leading ministers of the Roman Church; and exercised an almost unbounded sway over the mind of the superficial and time-serving bishop.  The Christians of the chief city were now split up into parties, some advocating the orthodox doctrine of the Trinity, and others abetting a different theory.  Callistus appears to have dexterously availed himself of their divisions; and, by inducing each faction to believe that he espoused its cause, managed, on the death of Zephyrinus, to secure his election to the vacant dignity.