This book is primarily a catalogue of those nearly-intact extant books containing the full music of the Mass made between the date of the Bohemian Revolution (July 1419) and the Battle of the White Mountain (November 1620). Two principal religious factions were active in Bohemia and Moravia during the period. The larger, the Utraquists, took communion in both bread and wine. The Roman Catholics, fewer but still numerous, followed the then relatively recent practice of using bread only. While graduals are important sources for the liturgy practised by Utraquists and Roman Catholics, many of them are also of great interest artistically and historically. Some of the more beautiful books were produced for use by the literary societies, later incorporated as guilds, which were responsible for the music in their churches. The information the books contain about the membership of the guilds, containing as it did most of the social strata of the towns, gives important information about the contemporary social structure and about the strength of Utraquism. Individual guild members often sponsored a page at the beginning of a mass set which was profusely decorated. The quality of the art and the evolution in the iconography can be appreciated in the book's 50 colour plates.