The principal claim of this thesis is that the mystical experience is a wide-ranging influence upon literature. It is a recurrent thematic concern of poets, novelists and playwrights; but even when mysticism is not an overt element in a text, analysis of its symbols can reveal references to emotions and experiences of a mystical character - as is frequently the case with fantasy. In a more essential way, certain widely-used techniques of poetry effectively reproduce the character of mystical events for the reader. Some theory does indeed imply that the mystical bearing is quite fundamental, at a certain level, to all creative literature. This thesis explores the link between mysticism and literature through widely differing examples, to show how it continues to be found in otherwise divergent texts and contexts. Indeed, no attempt is made to provide an exhaustive overview; rather, certain special areas of interest are represented by selected cases. Mystical elements in Modernism, for example (especially in T.S. Eliot and Virginia Woolf), are contrasted with Romantic attitudes to mysticism, which Wordsworth and Coleridge are taken to represent. A further goal is to analyse the character of literary mysticism, and to account for the connection between mysticism and literary practice. The view is adopted that the circumstances in which the infant first acquires language is of crucial importance in this regard, and that literary language often draws upon submerged recollections of these early circumstances. Literature, it is argued, can employ signs and patterns of symbolisation in ways that actually attempt to 'undo' many of the everyday functions of words. The ultimate ideal of such literary techniques is to 'reverse' the process by which language was acquired and to 'return' the reader to a state resembling pre-linguistic experience, a goal which has much in common with the ambitions of mystics. Jacques Lacan's theoretical writings touch at many points upon the early development of the child and the significance of its acquisition of language. This thesis consequently has recourse to Lacan's work and, where relevant, to related psychoanalytic writings by Sigmund Freud and Julia Kristeva. After an investigation of the main characteristics of mystical experience as such, the Introduction broadly outlines Lacan's theoretical position. Chapter 1 is concerned more specifically with Lacan's discussions of mysticism. Part Two (Chapters 2-4) deals principally with the links between mystical yearnings and the Romantic ideal of the 'sublime'. In Part Three (Chapters 5-7) the relation between mysticism and Modernist developments affecting both theme and artistic technique is examined in works by three writers: T.S. Eliot, Virginia Woolf, and Fernando Pessoa. Part Four discusses particular literary presentations of 'evil' and of 'good' as embodiments of mystical perceptions. Late nineteenth- and early twentieth-century 'supernatural' fiction is selected to represent the first case, and certain New Testament and early Christian texts the second.