In the fifteenth century, a Venetian mariner, Michael of Rhodes, wrote and illustrated a text describing his experiences in the Venetian merchant and military fleets. He included a treatise on commercial mathematics and treatments of contemporary shipbuilding practices, navigation, calendrical systems, and astrological ideas. This manuscript, "lost," or at least in unknown hands for over 400 years, has never been published or translated in its entirety until now. Volume 1 is a facsimile of the manuscript, reproduced in full color. The text is written out by hand and beautifully illustrated (probably at least in part by Michael himself), featuring color diagrams and illustrations of naval architecture, original drawings of astrological signs, calendrical charts, and a coat of arms Michael devised for himself. The book of Michael of Rhodes, a Greek by birth who integrated within Venetian society, is a unique document. It offers an exceptionally precious insight into the life, interests, and knowledge of a mariner whose career in the Venetian navy, on state missions and commercial expeditions extended from 1401 to 1443. In his numerous sailings between Venice, England, Egypt, and the Black Sea he gathered extensive data about shipbuilding, navigation, time reckoning, ports, maritime transportation, commodities, trade, and commercial calculation. This book will appeal to scholars of economic, maritime, and cultural history of the late Middle Ages.