Late eighteenth-century France saw the development of the machine’s first theoretical model, elaborated by Lazare Carnot. Alongside this development in mechanics, physiological treatises continued the tradition of describing the mind in terms of work. Moreover, a number of treatises emerged that attempted to define an elusive ailment, subsequently known as hysteria. A close reading of one such treatise by the Montpellier-trained physician Beauchêne brings into focus how late eighteenth-century physiology reflected a period-specific anxiety, which the work of Carnot only made too obvious: the irreversible arrow of time, the inevitable development (and progress) of civilization.