This book reconstructs and studies the music, liturgy, and illustrations of a twelfth-century manuscript from the Austrian monastery in Lambach. The manuscript was taken apart in the fifteenth century and subsequently sold to various collectors in the twentieth century. The pages are here brought together (albeit photographically) for the first time since the original manuscript was dismantled five centuries ago. The book includes a black-and-white facsimile of the recovered portion of the manuscript. Charts and tables are used to demonstrate how it compares to other twelfth-century liturgical manuscripts.