This new introduction replaces Marenbon's bestselling editions Early Medieval Philosophy (1983) and Later Medieval Philosophy (1986) to present a single authoritative and comprehensive study of the period. Completely re-written and updated to include the scholarship of last twenty years, this will be the standard companion for all students of medieval philosophy. It gives a lucid and engaging account of the history of philosophy in the Middle Ages - discussing the main writers and ideas, the social and intellectual contexts, and the important concepts used in medieval philosophy.