This book is based on a study of Italian business letters, diaries and commercial handbooks during the period 1300-1500. It shows the enormous variety of problems and products that faced medieval merchants and how they dealt with them. In spite of wars, piracy and a slow and unreliable mail system, Italian merchants ventured their capital on risky overseas trade. Superior commercial techniques - accounting methods, banks, insurance - have usually been used to explain their success. The author argues that other factory have to be considered. He suggests that the Italian business community had developed sophisticated networks based on trust and reciprocity for the control of their overseas business operations.