A substantial part of the French Collection highlights the often turbulent relations between church and state. One of the treasures of the collection is Le Songe du Vergier, an incunable printed circa 1500. Composed at the behest of Charles V in the 14th century in an effort to fortify the notion of royal sovereignty, Le Songe du Vergier introduces a dialogue between a knight and a cleric regarding the duty owed to the church and to the state. Works treating the Pragmatic Sanction of Bourges, Charles VII's controversial 1438 decree which dramatically restricted the Pope's powers and increased the King's, include two early treasures: Pragmatica Sanctio, an incunable printed at Lyon in 1497, and Les Ordonnances Royaulx des Feuz Roys Charles VII & Charles VIII (ca. 1512), which contains the text of the decree.
The Library also owns the writings of several controversial personalities from the period of religious strife during the 16th and 17th centuries, including those of François Hotman, the French Huguenot jurist who sought refuge with John Calvin during the St. Bartholomew's Massacre of 1572, and who estimated that 50,000 Protestants were killed in the whole of France during the two-month massacre. Also appearing in the collection are works of the outspoken Jansenist lawyer, Antoine Arnauld, whose celebrated 1594 presentation before the Parlement against the Jesuits and in favor of the University of Paris resulted in an order that the Jesuits leave Paris in three days and France in a fortnight.