Russian historian-medievalist and religious philosopher Lev Platonovich Karsavin was born in St. Petersburg, the son of a ballet dancer and master, and the brother of the famous ballerina Tamara Karsavina. He graduated from the Department of History of Petersburg University in 1906 and stayed there as a teacher, doing studies in medieval spirituality and culture. Being a disciple of the prominent medievalist Ivan Grews, he soon started to develop his own approach, which can be considered in retrospect as an early prototype of the method of the French Annales school. His first big monograph (1912) was devoted to the early history of the Franciscan Order and the heretical sects of the Waldenses and Cathars. His next monograph, Foundations of Medieval Spirituality in the Twelfth and Thirteenth Centuries, Mainly in Italy (1915), is an important theoretical work of a type close to future studies in historical...