Sociological research on chronic illness, and especially on the autobiographical writings of modern patients, has yielded insights into how chronic conditions alter fundamental relationships between notions of self, body, and time. The chronic part of “chronic illness” can disrupt perceptions of the linearity of time, yielding alternate temporalities grounded in bodily experience. In contemporary self-fiction, to chronicle a chronic condition is to juggle different kinds of time. But what about genres, like premodern historiography, that impose a linear, chronological framework? What is at stake when the narrative temporality of a medieval chronicle is filtered through the disrupted temporalities of a chronically impaired subject? This article interrogates these questions through the works of Gilles li Muisis (1272–1353). A Tournaisian abbot, Gilles authored both a Latin chronicle and of a set of vernacular poems situating his writerly activity within a very specific corporeal context: he writes both poetry and chronicle after cataracts have so impaired his vision that he can no longer carry out his administrative duties at the abbey of Saint-Martin—and, remarkably, he abandons his writing after a successful surgery restores his eyesight. The ways in which Gilles talks about his own bodily condition, in both the chronicle and the poems, constitute an elaborate metadiscursive frame whose ultimate effect is to construct the project of the chronicler as a kind of self-writing avant la lettre. With readings of both the Latin and the vernacular works, this essay shows that the chronicle is achieved through a series of subtle chronological and sensory displacements: Gilles’s chronic condition has enabled him to create an anachronic subject-position, outside of both linear historiographical time and the “body-time” of his impairment.