Thus, it came to pass, whether by accident or design, that Cummian, the great _Saoi_ or Doctor of the south, came all the way to Derry to visit the king, and administer spiritual consolation to him. But it seems the heart of the king still continued dry and impenitent. Then Cummian had recourse to prayer, and in order to obtain the gift of tears for his royal penitent, he composed, in honour of the Apostles, the very striking hymn in the _Liber Hymnorum_. It seems that this poetic prayer was efficacious; Domhnall became a sincere penitent, bewailing his sins with floods of tears. The prediction of Columcille was completely verified, and the Four Masters tell us that Domhnall died at Ard-folhadh, near Ballymacgrorty, in the Barony of Tirhugh, "after the victory of penance, for he was a year in mortal-sickness, and he used to receive the body of Christ every Sunday." As King Domhnall died in A.D. 642, we may fix this visit of Cummian at A.D. 640 or 641; the scholiast in the poem that caused the conversion of the king, tells us expressly, that it was "written in Derry," nigh to the ancient Aileach, the royal residence of the northern kings. By far the most important and interesting event in the life of Cummian was the part he played in the great Paschal controversy. We can at present give only the merest sketch of the history of this great discussion, so as to enable our readers to understand Cummian's share in the controversy. Of course the system of computing the date of Easter in use both in Ireland and England at the beginning of the seventh century was that which was introduced by St. Patrick himself, and which he acquired in the schools of France and Italy. From the very beginning, however, much diversity of practice existed between the Churches of the East and West, and even between some Churches in the West itself, in reference to the date of Easter Day. With a view to secure uniformity as far as possible, the Synod of Arles, to which Cummian refers, held in A.D. 314, prescribes in its first canon that the whole world should celebrate the Easter festival on one and the same day, and that the Pope, _according to custom_, should notify that day to all the Churches.[195] There were three British bishops present at that Synod. But the diversity of practice still continued, to the joy of the pagans and to the scandal of the faithful.