This book is based on Auction Sale No. 40 held April 3rd & 4th, 1989 by the Auction House Reiss & Auvermann. It comprises a collection of rare books about the age of exploration and the history of Portugal and Spain. Amongst the books referred to, with respect to the centuries of early exploration (AD 1500 to AD 1700), was a considerable number of items of great rarity and their hammer price rather often achieved many times the estimate. The contents of these books in many cases were so unusual that the brief comments printed in the auction catalogue needed additional explanation. Therefore, I made a selection of those 140 titles that seemed to me the most interesting and important ones. I added the original printed versions of more than 300 letters written by Jesuit missionaries (bound in 23 volumes and brochures, including some collective volumes or sammelbands) to their General in Rome between 1549 and 1629, mostly from Japan. Ample information, not only about the Christian mission, but also about the political situation in Japan in those days at the time when the Empire of the Rising Sun suffered from a disastrous civil war, is provided. Each entry in this book follows the same structure comprising four elements: 1. Author, title of the book, dates of printing, illustration, collation and binding. 2. Historical and bibliographical information. 3. Reference works. 4. Estimates, followed by hammer prices achieved, at that time in Deutsche Mark (DM). With a very few exceptions, we did not make use of abbreviations common in the antiquarian book trade. The ones used are pp. (page, pages); ll. (leaf, leaves); engr. (engraved); front. (frontispiece), cont. (contemporary). One of the key considerations for this volume is the practical benefits for western antiquarian booksellers if they happen to come across a book on this topic. This book not only gives detailed descriptions of each item, but also an indication as to pricing.