Lambert's rich volume covers comprehensively the history of Western heresy from its revival around the year 1000 to the time of Luther. It provides detailed accounts of all the notable heretical groups of the period, including the Cathars, the Spiritual Franciscans, the Lollards, and the Hussites. Lambert describes how the Church crushed the otherworldy Cathars, and how it rationalized burning Franciscans for imitating the poverty of Christ. He carefully weighs the evidence concerning the shadowy Free Spirit heresy and its influence on the female communes of the beguines. Just as carefully he follows Lollardy from its origins in the anticlericalism of John Wyclif to its rebellion against the English throne, and Hussitism from the career and judicial murder of the reformer Jan Hus through two decades of religious upheaval in Bohemia. Lambert then tells how Lollardy and Hussitism to find vindication in the Protestant revolt.