This is a cross-disciplinary examination of the mystical experience. It begins with survey data on the uncanny or anomalous experience, proceeds to consider neurobiological and cognitive psychological theory and data, examines philosophical positions and romanticism, proposes new biopsychophysical research compatible with both physical theory and data on sensory response. It then moves to consider Dionysios (called the 'fountainhead' of Western mysticism by William James) in terms of extant influences upon him in Byzantium (circa 600 AD). Examines Dionysios' mysticism and constructs a biography based on his situation and works. Also discusses mysticism's relationship to art and current secular expressions.