ABSTRACT
By 640, the southern Irish had conformed to what they considered to be the Roman practice for calculating Easter Sunday;1 the recalcitrants in the north held out, preferring to stick with their own traditions rather than accept a method which, as early as the sixth century, they knew to be mathematically unsound.2 Their defiance brought a stinging rebuke from the Irish cleric Cummian. Around 630 he wrote to Ségéne, the abbot of Iona, and to the recluse Beccán, warning of the consequences of particularism. Their appeal to ‘the traditions of the elders’ was a pretence, nothing more than ‘a cloak for your rejection’.3 They had a duty to lead and should be aware of the consequences for themselves and their flock if they led badly. According to Bede’s Historia ecclesiastica, around the same time the Irish received another missive on the proper celebration of Easter, this time from the pope, Honorius. It was followed in 640 by yet another letter from Rome in which the pope, now John Iv, told the Irish that their refusal to accept guidance in this matter was tantamount to heresy. The letter is quoted in extenso by Bede and, like Cummian’s, was addressed to northern clerics who are named in the opening salutation.4 The Tomianus who heads the list is probably Tomméne mac Rónáin, bishop or abbot of Armagh, and the ten clerics named with him have been identified as leaders in the northern church. The Segenus who appears among them is probably the Ségéne to whom Cummian had written less than a decade before.
