From his first article, published in 1958, Albert Derolez's scholarly interests have evolved and expanded so as to embrace all aspects of the medieval book?: script, with his magisterial Palaeography of Gothic Manuscript Books (2003); form, whose understanding his Codicologie des manuscrits en écriture humanistique sur parchemin (1984) did much to advance; and content, too, for he has brought out scholarly editions of works by Guibert of Gembloux (1989) and Hildegard of Bingen (1996). His doctoral research on the encyclopediaof Lambert of Saint-Omer has given rise to numerous publications culminating in The Making and Meaning of the Liber Floridus (2015). His tireless effort has carried to completion the seven volumes of Corpus Catalogorum Belgii, an indispensable reference for all who study the history of libraries. To mark the sixtieth year of this rich career, thirteen scholars from eight countries have produced a volume of essays honouring the man who was to some of them a teacher, to others a collaborator, to all a friend and model. The subjects covered are those that have most interested Prof. Derolez and have earned him worldwide renown.