My thesis is that many of Tennyson's apparently paranormal experiences are explicable in terms of temporal lobe epilepsy; and that a study of the occurrence, in the work of art, of phenomena associated with these experiences, may be useful in elucidating the workings of the aesthetic imagination. A body of knowledge relevant to paranormal experience in Tennyson's life and work, assembled from both literary and biographical sources, is applied to a Subjective Paranormal Experience Questionnaire, compiled by Professor V.M. Neppe, in order to establish the range of the poet's apparently "psychic" experiences. The information is then analysed in terms of the symptomatology of temporal lobe epilepsy (TLE), and the problems of differential diagnosis are considered. It is shown, by means of close and comparative analyses of a number of poems, that recurring clusters of images in Tennyson's poetry may have their genesis in TLE. These images are investigated in terms of modern research into altered states of consciousness. They are found to be consistent with a "model" of the three stages of trance experience constructed by Professor A.D. Lewis-Williams to account for shamanistic rock art in the San, Coso and Upper Paleolithic contexts. My study of the relevant phenomena in the work of a nineteenth century English poet would seem to offer cross-cultural verification of the applicability of the model to a range of altered-state contexts. This study goes on to investigate some of the psychological processes which may influence the way in which pathology is manifested in the poetry of Alfred Tennyson. But, throughout the investigation, the possible effects of literary precursors and of other art forms are acknowledged. The subjective paranormal phenomena in Tennyson's poems are compared not only with some modern neuropsychiatric cases, but also with those of several nineteenth-century writers who seem to have had similar experiences . These include Dostoevsky and Edward Lear, who are known to have been epileptics, and Edgar Allan Poe. Similarity between some aspects of Tennyson's work and that of various Romantic poets, notably Shelley, is stressed; and it is tentatively suggested that it might be possible to extrapolate from my findings in this study to a more general theory of the "Romantic" imagination.