In the 12th century the "Book of the Soul" by the philosopher Avicenna was translated from Arabic into Latin. It had an immense success among scholastic writers and deeply influenced the structure and content of many psychological works of the Middle Ages. The reception of Avicenna's book is the story of cultural contact at an impressively high intellectual level. The present volume investigates this successful reception using two approaches. The first is chronological, tracing the stages by which Avicenna's work was accepted and adapted by Latin scholars. The second is doctrinal, analyzing the fortunes of key doctrines. The sense of the original Arabic text of Avicenna is kept in mind throughout and the degree to which his original Latin interpreters succeeded in conveying it is evaluated.