During the later Middle Ages (twelfth to fifteenth centuries), the study of chronology, astronomy, and scriptural exegesis among Christian scholars gave rise to Latin treatises that dealt specifically with the Jewish calendar and its adaptation to Christian purposes. In Medieval Latin Christian Texts on the Jewish Calendar C. Philipp E. Nothaft offers the first assessment of this phenomenon in the form of critical editions, English translations, and in-depth studies of five key texts, which together shed fascinating new light on the avenues of intellectual exchange between medieval Jews and Christians.

The study of time, astronomy, and calendars, has been closely intertwined in the history of Western culture and, more particularly, Jewish tradition. Jewish interest in astronomy was fostered by the Jewish calendar, which was based on the courses of the sun and the moon, whilst astronomy, in turn, led to a better understanding of how time should be reckoned. Time, Astronomy, and Calendars in the Jewish Tradition, edited by Sacha Stern and Charles Burnett, presents a wide selection of original research in this multi-disciplinary field, ranging from Antiquity to the later Middle Ages. Its variety of approaches and sub-themes reflects the relevance of astronomy and calendars to many aspects of Jewish, and more generally ancient and medieval, culture and social history. Contributors include: Jonathan Ben-Dov, Reimund Leicht, Marina Rustow, Francois de Blois, Raymond Mercier, Philipp Nothaft, Josefina Rodriguez Arribas, Ilana Wartenberg, Israel Sandman, Justine Isserles, Anne C. Kineret Sittig, Katharina Keim, and Sacha Stern

The Gregorian calendar reform of 1582, which provided the basis for the civil and Western ecclesiastical calendars still in use today, has often been seen as a triumph of early modern scientific culture or an expression of papal ambition in the wake of the Counter-Reformation. Much less attention has been paid to reform's intellectual roots in the European Middle Ages, when the reckoning of time by means of calendrical cycles was a topic of central importance to learned culture, as impressively documented by the survival of relevant texts and tables in thousands of manuscripts copied before 1500. For centuries prior to the Gregorian reform, astronomers, mathematicians, theologians, and even Church councils had been debating the necessity of improving or emending the existing ecclesiastical calendar, which throughout the Middle Ages kept losing touch with the astronomical phenomena at an alarming pace. Scandalous Error is the first comprehensive study of the medieval literature devoted to the calendar problem and its cultural and scientific contexts. It examines how the importance of ordering liturgical time by means of a calendar that comprised both solar and lunar components posed a technical-astronomical problem to medieval society and details the often sophisticated ways in which computists and churchmen reacted to this challenge. By drawing attention to the numerous connecting paths that existed between calendars and mathematical astronomy between the Fall of Rome and the end of the fifteenth century, the volume offers substantial new insights on the place of exact science in medieval culture.

Calendars in the Making investigates the Roman and medieval origins of several calendars we are most familiar with today, including the Christian liturgical calendar, the Islamic calendar, and the week as a standard method of dating and time reckoning.

Critical edition of previously unpublished works by a key philosopher of the fifteenth-century Low Countries Peter de Rivo (c.1420–1499), a renowned philosopher active at the University of Leuven, is today mostly remembered for his controversial role in the quarrel over future contingents (1465–1475). Much less known are his contributions to historical chronology, in particular his attempts to determine the dates of Christ’s birth and death. In 1471, Peter made an original contribution to this long-standing discussion with his Dyalogus de temporibus Christi, which reconciles conflicting views by rewriting the history of the Jewish and Christian calendars. Later in his career, Peter tackled the issue of calendar reform in his Reformacio kalendarii Romani (1488) and engaged in a heated debate with Paul of Middelburg on the chronology of Christ. This book edits the Dyalogus and Reformacio and sets out their context and transmission in an extensive historical introduction.

This book offers an internalist view on the history of astrology by studying the case of S. Belle, an astrologer who lived in late fifteenth-century France. It addresses his methods of work, his process of learning, and his practice.

In Cosmos, Liturgy, and the Arts in the Twelfth Century, Margot E. Fassler takes readers into the rich, complex world of Hildegard of Bingen’s Scivias (meaning “Know the ways”) to explore how medieval thinkers understood and imagined the universe. Hildegard, renowned for her contributions to theology, music, literature, and art, developed unique methods for integrating these forms of thought and expression into a complete vision of the cosmos and of the human journey. Scivias was Hildegard’s first major theological work and the only one of her writings that was both illuminated and copied by scribes from her monastery during her lifetime. It contains not just religious visions and theological commentary, but also a shortened version of Hildegard’s play Ordo virtutum (“Play of the virtues”), plus the texts of fourteen musical compositions. These elements of Scivias, Fassler contends, form a coherent whole demonstrating how Hildegard used theology and the liturgical arts to lead and to teach the nuns of her community. Hildegard’s visual and sonic images unfold slowly and deliberately, opening up varied paths of knowing. Hildegard and her nuns adapted forms of singing that they believed to be crucial to the reform of the Church in their day and central to the ongoing turning of the heavens and to the nature of time itself. Hildegard’s vision of the universe is a “Cosmic Egg,” as described in Scivias, filled with strife and striving, and at its center unfolds the epic drama of every human soul, embodied through sound and singing. Though Hildegard’s view of the cosmos is far removed from modern understanding, Fassler’s analysis reveals how this dynamic cosmological framework from the Middle Ages resonates with contemporary thinking in surprising ways, and underscores the vitality of the arts as embodied modes of theological expression and knowledge.