 Hartley formed the adjective “automatic” from an existing noun, “automaton,” to describe movements such as “the motions of the heart, and the peristaltic motion of the bowels” (OM 1, Introduction). Such “originally automatic” motions are homeostatic: As a heart beats, the alternation of contraction and relaxation is maintained and modified in response to the needs and experiences of the organism (OM 1, prop. 19).