For the controversy is not merely as regards the day, but also as regards the form itself of the fast. For some consider themselves bound to fast one day, others two days, others still more, while others [do so during] forty: the diurnal and the nocturnal hours they measure out together as their [fasting] day. And this variety among the observers [of the fasts] had not its origin in our time, but long before in that of our predecessors, some of whom probably, being not very accurate in their observance of it, handed down to posterity the custom as it had been [introduced to them] through simplicity or private fancy. And yet nevertheless all these lived in peace one with another, and we also keep peace together.
Thus, in fact, the difference [in observing] the fast establishes the harmony of [our common] faith. … And when the blessed Polycarp was sojourning in Rome in the time of Anicetus, although a slight controversy had arisen among them as to certain other points, they were at once well inclined towards each other [with regard to the matter in hand], not willing that any quarrel should arise between them upon this head.