With Flann O'Brien now widely acknowledged as a subversive genius of early post-modernism, Flore Coulouma gives the "question of language" a central position in his literary identity. Tracing O'Brien's philosophy of language to the convoluted structure of his writing, Coulouma demonstrates how his bilingualism and ambiguous relation to language inspired his satirical fiction and chronicles, and develops a series of narrative oppositions: orality and literacy, truth and fiction, authority and legitimacy, native and national language(s). Using such dialectical oppositions to stage O'Brien's literary representation of the diglossic relationship of speakers to their native tongue, this book casts light on O'Brien's own intuitions about the failures and achievements of language, the logic of fiction, the relation between language and knowledge, and the impossibility of a nation cut off from its original tongue finding its linguistic identity.