This first chapter describes the objectives of the book. The general introduction explains the importance of individual "doctrinal" authors (next to legislators and judges) for the evolution of the "Western legal tradition", consisting of both the (English) common law and the continental (Roman) civil law. The chapter gives a brief overview of the birth and first centuries of the Ius Commune of Roman and canon law, and how the incunabula of the fifteenth century brought the earlier manuscript tradition to a broader public, starting an ongoing ramification of legal works through the following centuries. In the chapter the editors explain how they came to a list of 150 of the most important "doctrinal" works and what kind of information each of the entries contain on the author on the one hand and on his most relevant significant legal work on the other. The criteria for the inclusion of each book are explained and the role of iconography in legal imprints is briefly described.