Note 230 — RESEARCH IV.
Reading edition
The immortal Hartley has demonstrated that all our motions are originally automatic, and generally produced by the action of tangible things on the muscular fibre.
The common actions of adults may be distinguished into two kinds; voluntary actions, and mixed automatic actions. The first are produced by ideas, or by ideas connected with passions. The second by impression, or by pleasure and pain.
In voluntary action, regular associations of ideas and muscular motions exist: as when a chemist performs a pre-conceived experiment.
In mixed automatic actions, the simple motions produced by impression are connected with 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.
Evidently the muscular actions produced by nitrous oxide are mixed automatic motions.