Les livres etaient les principaux instruments des humanistes. Erasme, Lipse, Torrentius et tant d'autres y puisaient non seulement leur savoir universel, mais divulguaient aussi par cette voie leurs idees scientifiques, philosophiques, linguistiques et litteraires. Au debut de la Renaissance cela se faisait toujours par des livres manuscrits, mais l'invention de l'imprimerie a declenche une veritable explosion de la communication et partout en Europe nous voyons naitre des bibliotheques privees importantes. Some of these private libraries are world-wide renowned because of their near-intact nature. Thus we can now still visit the libraries of Cusanus and Beatus Rhenanus. However, these are exceptions. The majority of libraries have become dispersed and can only be reconstructed after extensive investigations. This book aims to shed light on as many aspects of the humanist libraries as possible and in doing so demonstrate their importance for the functioning of networks of scholars from the 15th to the 17th century.