The Imitation of Christ, now more or less definitively attributed to Thomas a Kempis, who developed it in four separate but related tracts during the second quarter of the fifteenth century, is a paradigm text of the post-schismatic age in which temporal governments gradually assumed responsibility for the religious unity of their subjects, whether Catholic or, after 1530, Lutheran, Anglican or Calvinist. Its call to self-imposed discipline and the prospect of inward consolation which it would impart by submission to the will of God was well suited to the carefully educated and serious-minded individuals, both lay and clerical, on whom government of any kind depended. Princes and ministers, city magistrates, Spanish soldiers, Dutch scholars and English office-holders with their friends and families could all be reassured by its message of hope. As a consequence it is extant in over 800 manuscript and innumerable printed copies. Maximilian von Habsburg has undertaken the immense labour of surveying the 639 editions in Latin and a dozen vernacular languages, including Croatian and Japanese, which appeared before 1650; further than that, he has explored the motives of the various editors and translators, whose projects appealed across the noise of Reformation polemic to the still, small voice of conscience and interior contemplation, and reveal to us another side to the religious culture of the sixteenth century. The Imitatio had been an item in the spiritual library circulated in manuscript by the religious orders engaged in copying, the Carthusians, Celestines and Augustinian canons; it was translated into English at the royal foundation of Sheen in the mid-fifteenth century, and into Portuguese in 1467 at the instance of Isabella, duchess of Burgundy; Cardinal Cisneros commissioned a Spanish translation, and Thomas More recommended it. The book was sanctioned therefore for lay use by a variety of authoritative persons. More surprising was its fortune in the Protestant world, where it circulated in an etiolated form, shorn of its fourth, eucharistic book and its references to monasticism and the cult of saints. The animating force seems to have been the independent Protestant Caspar Schwenkfeld, whose translation appeared in 1531, and further versions appeared by Leo Jud (1539), who was close to the magistracy of Zwinglian Zurich, and by Sebastian Castellio (1551). English translations by the strong Protestants Edward Hake and Thomas Rogers, especially the latter, came from the heart of the Elizabethan establishment. The Imitatio, it seems, steadied the consciences of Protestant statesmen. Its fortune was no different in the Catholic world, where the Jesuit order, the principal heir to the fifteenth-century orthodox reformers and their spiritual library, took the lead in circulating the text. Ignatius Loyola made it an integral part of Jesuit training; its emphasis on the limitations of human learning was a necessary corrective to a learned order. But it was equally edifying for lay pupils in Jesuit colleges, and for its foreign missions: the Japanese translation incorporated phrases which would have resonated with Buddhist readers. This study does not tell us how readers reacted to the Imitatio, which would indeed fill another book. But Maximilian von Habsburg has provided a splendid guide to the fortunes of a fifteenth-century classic in a divided Reformation world, which takes us to some unexpected new vantage points over that fragmented landscape.