This remarkable epistle affords a striking proof, not only of Cummian's own learning, but of the high efficiency of the schools of his native land, in which he studied. He gives the Hebrew, Greek and Egyptian names of the first lunar month. He refers to almost every cycle, and emendation of a cycle, of which we have any account, briefly, indeed, but sufficiently to show that he was acquainted with them, and with the decrees of synods, and with the passages of the Fathers that make reference to them. Above all things, he insists upon the unity of the Church, and incontestably establishes the Irish tradition in his own time, that the Irish Church was founded from Rome, that Rome is the Source of Unity, the final Court of Appeal, and the Mother of the Irish, as of all other Churches. The text is unfortunately somewhat corrupt, and the style wants polish; but, though in this respect Cummian is inferior to several Irish writers of the seventeenth century, his Latin is much superior to that of several ecclesiastical documents that we have seen in our own nineteenth century. The _Liber de Mensura Poenitentiarum_, cannot with certainty be ascribed to Cummian Fada; but it is highly probable that he was the author. It was preserved like so many other invaluable Irish MSS., in the Monastery of St. Gall, and has been published in the _Bibliotheca Patrum_, and, together with the Paschal Epistle, has been republished by Migne.[201] We have seen that Cummian was regarded by the Abbot of Hy as a great moralist, and it may be that the same Segienus was the "faithful friend," whom the author addresses--mi fidelissime--in the prologue. The treatise consists of fourteen chapters, giving the canonical penances assigned to sins of various kinds. It treats of these sins in the most minute detail, but contains little original matter; for the penances are, in most cases, taken from the works of the Fathers and the penitential canons of various early Councils. But it shows how carefully these matters were attended to in our early Irish Church, and is another striking monument of its ecclesiastical learning. Cummian Fada has not unfrequently been confounded with Cummian Finn, the nephew of Segienus, Abbot of Hy. The latter wrote a life of St. Columba, to which Adamnan refers, and most of which he, Adamnan, inserted in the Third Book of his own Life of St. Columba. The Paschal Epistle has also been attributed to him, but without any grounds. The intrinsic evidence of the letter itself shows that it was written by a prelate of the southern half of Ireland; he speaks of Ailbe, Brendan, and the rest as "our fathers and predecessors;" he had accepted the Roman usage which Hy and its family refused to accept for many years after; and he uses in reference to St. Peter the very peculiar expression, "clavicularis," which is also used by the author of the poem in honour of the Apostles, which was undoubtedly the work of Cummian Fada, the Bishop of Clonfert.