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 bouts of frenzy, melancholy and ever-scarcer lucidity until his death in 1422. The king's scarcely mentionable malady was mirrored at every level of social experience, from the irrational civil war through which the body politic tore itself apart,...