As printing from movable type was perfected in the fifteenth century, the mysteries of its practice were guarded by a privileged few. The rapid spread of the new art depended on the development of a reliable mechanism for transferring knowledge, and printers naturally adapted the established practices of the medieval craft guilds. In this way, the art of printing was preserved and sustained, often carefully veiled from outsiders, and always the product of years of close study and practice. By the end of the seventeenth century, however, the pioneers of manufacturing technology and scientific inquiry were prying away at the rotting doors of medieval trade secrecy. The Printer’s Manual – An Illustrated History is based on an exhibition of the same name, displayed at the Melbert B. Cary Jr. Graphic Arts Collection, and shows the history of printing manuals from 1683 to the end of the nineteenth century, including some of the rarest in existence.