Book excerpt: Alexander III was one of the most important popes of the Middle Ages and his papacy (1159-81) marked a significant watershed in the history of the Western Church and society. This book provides a long overdue reassessment of his papacy and his achievements, bringing together thirteen essays which review existing scholarship and present the latest research and new perspectives. Individual chapters cover topics such as Alexander's many contributions to the law of the Church, which had a major impact upon Western society, notably on marriage, his relations with Byzantium, and the extension of papal authority at the peripheries of the West, in Spain, Northern Europe and the Holy Land. But dominant are the major clashes between secular and spiritual authority: the confrontation between Henry II of England and Thomas Becket after which Alexander eventually secured the king's co-operation and the pope's eighteen-year conflict with the German emperor, Frederick I. Both the papacy and the Western Church emerged as stronger institutions from this struggle, largely owing to Alexander's leadership and resilience: he truly mastered the art of survival.