This essay addresses the socio-cultural potential of phreno-mesmerism in the mid-nineteenth century and how its good intentions were frustrated by its uncanny discourse. Supporters of phreno-mesmerisms social agency dreamed that the physiological make-up of future generations could be determined by engineering sexual partnerships. But the more earnestly the new hybrid science was advanced as a tool of social change, the more the discourse of phreno-magnetism proved unwieldy. In effect, the discourse represents a double-bind, intertwining sex and gender, essentialism and constructionism, science and the occult, materialism and Gothic. The article focuses of Elliotson‘s enthusiasm for uniting phrenology and mesmerism in his notorious Letter On Mesmeric Phrenology and Materialism (1843).