Based on the medical and literary meanings of “irritability,” this essay argues that negative capability describes the historical and embodied nature of the writing process itself, a process that is vividly materialized in the manuscript version of Keats’s “This living hand.” The meanings of ‘irritability’ in medicine and literary history illuminate the role of the body in poetic production and textual mediation. ‘Irritable reaching’ suggests a paradox of contraction and extension, and this paradox reappears in the poem’s haunting gesture, in which a spectral speaker endeavors to ‘hold’ his hand ‘towards’ the reader. Negative capability, in light of its physiological significance, can be understood as a goal that is briefly attained during the moments when inspiration, influence, and composition are simultaneous and when acquiescence to cultural belatedness facilitates rather than forestalls literary composition.