Writing about the effect of inhaling nitrous oxide (laughing gas) in 1800, a young Humphry Davy described the experience by appealing to the ideas of the ‘immortal’ philosopher and physician David Hartley (1705–57). Likening the muscular actions induced by nitrous oxide inhalation to ‘common pleasurable feelings or strong emotions’, Davy ascribed the generation of these to what he called Hartley’s category of ‘mixed automatic actions’, wherein a ‘series of motions formerly voluntary, but now produced without the intervention of ideas: as when a person accustomed to play on the harpsichord, from accidentally striking a key, is induced to perform the series of motions which produce a well-remembered tune’.1 Davy’s comparison of the involuntary actions generated via a chemical influence with the automatic actions undertaken by a musician at a keyboard forges a rather unusual connection between sound and sense: rather than deciding to make music, Davy’s performer is compelled to play after unintentionally striking a key. Here, mind and body are inextricably linked in what seems to be a misprision of Hartley’s famous analysis of the stages involved in learning to play at a keyboard in his Observations on Man (1749). For Hartley, the example of acquiring skill at a musical instrument constituted a supreme case of the transformation of increasingly complex and rational sequences of intentional mental commands into involuntary physical movements, that is, the kinds of actions he deemed ‘secondarily automatic’. For Davy, rather, the sound of the harpsichord was prior: mistakenly hitting a key activated this complex chain of actions, without the performer’s desire or volition.

In his celebrated essay on insanity in the Dictionnaire des sciences médicales (1816), French psychiatrist Étienne Esquirol marvelled at the earlier custom of allowing asylum inmates to attend theatrical productions at Charenton.