At the turn of the fifteenth century it must have seemed to many French people that the world was going mad. King Charles VI suffered his first bout of mental illness in 1392, and he underwent intermittent periods of frenzy, melancholy, and ever-scarcer lucidity until his death in 1422. The king's malady was mirrored at every level of social experience, from the irrational civil war through which the body politic tore itself apart, to reports of elevated suicide rates among the common people. In this political environment, where affairs of state were closely linked to the ruler's mental state, French writers sought new ways of representing the psychological dynamics of the body politic.

The delicacy of the king's condition demanded tact, a constraint that gave rise to unexpected literary representations of moments of mental and political breakdown. In this book I expose the innovative mix of organic and inorganic metaphors through which late medieval French writers explored the relationship between mind, body, and government: as a key example of this confrontation of the organic and the inorganic, I consider texts describing mental illness or intellectual impairments as a form of “rust.” While medieval writers frequently allegorize the state itself as a body, with the ruler at its head, they construct the mind within that head of state as a machine. From the characterization of the intellect as engin to the designation of four of the chief virtues as “cardinal” (from cardo, “hinge”), both cognitive function and moral decision-making carry with them notions of the mechanistic movement of metallic parts. Breakdowns of these processes vital to good government of self and of state result in the mind's metaphoric immobilization with rust. Such language becomes increasingly common over the course of the fourteenth century. In the context of Charles VI's reign and the crises that stemmed in part from his mental incapacity, inorganic metaphors, and more particularly the language of rust, offer an innovative and politically neutral instrument with which to represent the imbalanced mind and rewrite its ethical and political impact.