Much of the folk music tradition of ancient Ireland was lost to time. It was not until the 18th century that a wave of Irish nationalism spurred the composers of Ireland to notate the old tunes of their motherland. Thomas Moore was a leading Irish composer of this movement. His arrangements of Irish folk tunes became fan10us and widely known during his lifetime. Due to Moore's work, songs such as "The Last Rose of Summer" are still familiar to most Westerners and are still being arranged by contemporary composers. In this paper I explore the mysterious and stormy background of these ancient songs, infused with Gaelic, medieval Christian, and 18th century harmonic elements.