Book excerpt: Sweeney Astray is Seamus Heaney's version of the medieval Irish work Buile Suibne. Its hero, Mad Sweeney, undergoes a series of purgatorial adventures after he is cursed by a saint and turned into a bird at the Battle of Moira. Heaney's translation not only restores to us a work of historical and literary importance but offers the genius of one of our greatest living poets to reinforce its claims on the reader of contemporary literature.