From Elert's Eucharist and Church Fellowship in the First Four Centuries (page 196:
"How did the presiding bishop from Alexandria bring this breakaway under control? He could not yet say with Augustine, 'Compel them to come in,' for the police were not yet at the church's disposal. He did what one has a right to expect of a true chief shepherd. He himself went to see the schismatics and heretics, gathered their presbyters and teachers together, and talked things over with them. 'For three days I sat with them from early in the morning until evening, seeking to correct what had been written [by Nepos]' It was all most orderly and brotherly. Precise questions were put and answers given. No one got pigheaded. Each took the other's criticisms seriously and sought to learn. The result was complete agreement. The schism was healed.
In this instance there were a number of especially propitious secondary factors. The schism was new and local. The false teachers were reasonable people. All the patience and wisdom of that truly spiritual man Dionysius would scarcely suffice with the Jehovah's Witnesses of today. Things would likely not have gone so smoothly if his opponent had been another presiding bishop. There were not only polemics in the church before Constantine but rivalries too. When fraternal relations were restored, and this was the rule in the church of the majority, it was not without jealous safeguards for personal spheres and powers. Yet even so there was as little need then as in the schism of the Egyptian Adventists for either Caesar's initiative or help toward unity."