Knock ou Le Triomphe de la Médecine [Knock, or the Triumph of Medicine] (1923) is a satirical play by Jules Romains parodying the hierarchical power relationship between patient and doctor and the supposed infallibility of science in the early twentieth century. Drawing on the phenomenological work of German physician Herbert Plügge (1970), I argue that the play exploits the physical interconnections between the healthy body and the sick body to present health as a deceptive state of hidden or imminent illness. By anticipating illness, the play shatters the illusion of health in ways that are ethically, psychosocially, and biomedically salient.