In 1844, an obscure and little-remembered American theorist, A. Yorke (no further identification is available), published a theory of mesmerism based on absorption, i.e., mental concentration. Unlike Mesmer's conceptualization of animal magnetism as a biological fluid, however, Yorke's theory emphasized the psychological importance of the mutual interaction between mesmerist and subject. This paper discusses the latter's theory of absorption as an important development in neo-mesmerism, the circumstances that led him to his conclusions, and his role in advancing our knowledge of the historical origins of modern hypnosis.