Pierre d’Ailly’s De falsis prophetis II and the Collectiones of William of Saint-Amour

One of the main sources for our understanding of Pierre d’Ailly’s (1351-1420) apocalyptic conceptualization of ecclesiastical history and reform is the Tractatus de falsis prophetis II (DFP II). This article shows how the apocalyptic content of this work is entirely comprised of carefully rewritten passages from William of Saint-Amour’s (1200-1272) Collectiones. Given d’Ailly’s promotion of the mendicant ideal and his use of Joachite prophecy, his repurposing of the antimendicant and anti-Joachite apocalypticism of the Collectiones to speak of the danger of hypocritical ecclesiastical prelates during the Western Schism is surprising. Both d’Ailly and Saint-Amour, however, made extensive use of the prophecies of Hildegard of Bingen (1098-1179). This article argues that it was the Hildegardian nature of Saint-Amour’s apocalypticism-particularly his emphasis on an alliance between false religious and secular rulers of which Hildegard had prophesied in her “Cologne Prophecy” - that explains d’Ailly’s use of the Collectiones in DFP II.