Reference is made in our ancient extant manuscripts to several 'Books' now lost, which are said to have been written before the arrival of St. Patrick in Ireland. It is unnecessary, however, to refer to those in detail; because any statements about their character and origin can be little better than mere conjecture. O'Curry names several of them, and tells all that can possibly be known about them. The "Cuilmen" appears to have been one of the oldest and most celebrated, because it contained the great epic of ancient Erin known as the "Tain Bo Chuailnge." Another famous ancient 'Book,' now lost, was the "Cin Droma Snechta," or the Vellum Stave Book of Drom Snechta, as O'Curry translates it. It is quoted in the _Book of Ballymote_, and in the _Book of Lecan_. Another lost work, to which we have already referred, was the _Book of Ua Chongbhail_. It was extant in the time of Keating, who quotes it as one of his authorities, but it has since been unfortunately lost, and nothing is now known of its contents. II.--SEDULIUS. It is said, however, that there were not only pagan writers and scholars, like Cormac Mac Art, in Ireland before the time of St. Patrick, but that several celebrated Christian writers, who flourished before the advent of our national Apostle, were of Irish birth or parentage. And this is the opinion, not merely of superficial writers, but of grave and learned men like Colgan, Usher, and Lanigan; and what is more, it has been admitted by foreigners as well as by our native authorities. These authorities have claimed for Ireland the great glory of having given birth to the celebrated Sedulius, the Christian Virgil, as he has been most appropriately called. The more doubtful honour of producing Caelestius, the associate of the heresiarch Pelagius, has been also claimed for Ireland; and according to others Pelagius himself was at least of Irish extraction. We propose to examine at some length the history of these writers, and especially to examine the evidence in favour of their alleged Irish origin. In the first place we shall give a full account, so far as it is now possible to ascertain his history, of the celebrated poet Sedulius.