Edward O’Reilly (Dublin [?] 1765 – Dublin 1830) came from an obscure background; his interest in Irish-language sources was triggered by the acquisition of discarded manuscripts; apparently, he was never fluent in the spoken language. He started to collect folk music in the 1810s and published an Irish-language dictionary (with appended grammar) in 1817, Sanas Gaoidhilge-Sagsbheárla. In the same year he was involved in the foundation of the Iberno-Celtic Society, the successor to the earlier, defunct Gaelic Society of Dublin (1806-08), of which he had also been a member. Unlike his predecessor Theophilus O’Flanagan, O’Reilly managed to place his knowledge under the auspices of the social and intellectual elite of the day: his dictionary (published by subscription) was dedicated to the duke of Kent, and his Iberno-Celtic Society had the duke of Leinster as its president; it included Royal Irish Academy members such as George Petrie and James Hardiman. O’Reilly’s most important publication is a 200-page Chronological account of nearly four hundred Irish writers, with a descriptive catalogue of their works, which occupies the sole volume of the Iberno-Celtic Society’s Transactions(1820). It constitutes, alongside Charles O’Conor’s Rerum Hibernicarum scriptores veteres of 1814-28, the first, inventorizing move towards a history of Gaelic literature.

O’Reilly’s work with the Iberno-Celtic Society also seems to have paved the way for a renewal of interest in Irish antiquities in Royal Irish Academy circles (which following the 1798 rebellion had become a taboo topic): in 1825 O’Reilly published, in the Academy’s Transactions, a very substantial “Essay on the nature and influence of the ancient Irish institutes, commonly called the Brehon Laws, and of the number and authenticity of the documents whence information concerning them may be derived; accompanied by specimens and translations from some of their most interesting parts; with an appendix, containing a catalogue of the principal ancient Irish laws, to be found in the MSS library of Trinity College, and other libraries”. This was itself the first signal of legal history entering into the purview of Irish historicism; it was later to lead into the Academy’s great project of editing the Brehon Laws, prepared by O’Reilly’s successors John O’Donovan and Eugene O’Curry.

O’Reilly was also, briefly, employed on the Ordnance Survey of Ireland, which was to provide such an important professional platform for his more successful successor John O’Donovan. Although his successors found much fault with his linguistic scholarship, he laid the basis for the Ordnance Survey’s toponymical interest, and established the Gaelic root-forms of local place-names.