What seems absolutely certain is, that during his stay at the University he must have availed himself to the full of opportunities presented by the library for which Trinity College is famous. Here, no doubt, he laid the foundation of that Oriental learning in which he was second to no Irishman of his day, and probably to few Englishmen. It is hardly too much to say that in the early part of the century Orientalism was comparatively untrodden ground. Sir William Jones had indeed, many years before, thoroughly explored this field of knowledge, but the results of his splendid labours had not as yet been properly assimilated by the general mass of readers, or supplemented to any remarkable extent by other workers in the same field. Hence the scope of European knowledge of the East was by no means so extensive then as now; and an enthusiastic student thereof, which O’Brien undoubtedly was, had it in his power to acquire an almost complete mastery of the subject, so far as it was then known. It was one peculiarly fitted to his ardent, dreamy, and speculative nature. He read, he pondered, he divined, he foresaw. Dark places in the history of his own country began to grow clear in the light of this Eastern dawn. Hitherto, like so many of his compatriots, he had found no way of accounting for the extraordinary contrast between the distinctive superiority of “the Ireland that _was_” and the relative obscurity of “the Ireland that _is_.” To what, he must apparently have asked himself, was the fact to be attributed, that a people who in days of old were admittedly pre-eminent in learning and civilisation, should have afterwards lost all claim to such distinction; or how was it that, in a land covered with the ruins of structures evincing the ripest skill and most fanciful artistic device, architecture should have sunk to a level that was almost barbarous? Why was it that this decadence did not take place gradually, as one would expect, but was plainly the result of a sudden check that stopped the erection of such edifices at once and for ever? Why were the materials, structure, and conformation of the edifices in question so different from those of other ancient buildings found in their immediate neighbourhood? Why had their sculptured ornamentation reference to what was unconnected with, nay even opposed to, the teachings of that religious faith to which its execution was attributed; and why did the peasantry, inheriting the tradition of bygone ages, not recognise them as identified with that religion? Questions like these are very stimulating to inquisitive young souls, which usually become fired with an ambition to solve them; and as O’Brien pored over Sir William Jones and _The Asiatic Researches_--not to mention his beloved, though decried, Herodotus--it was only natural that he should draw certain conclusions from the undoubted affinity that exists between the languages, folk-lore, customs, superstitions, and modes of