""Gnosticism in the Middle Ages"" is a book written by John Yarker that explores the history and influence of Gnosticism during the medieval period. The book covers the origins of Gnosticism, its development in the early Christian church, and its spread throughout Europe during the Middle Ages. Yarker examines the various Gnostic sects and their beliefs, including the Cathars, Bogomils, and Albigensians, and their impact on medieval society and culture...