The book discusses principally the iconography and text of a mid 15th century copy of the mystical treatise Horloge de Sapience in the most sumptuously illuminated ms. known of the text. Each of the 36 illuminations is discussed in turn, with reference to their pictorial traditions, to the French textual matter and to a unique contemporary commentary, called the Déclaration des hystoires. The Déclaration is one of the earliest essays in the history of art criticism to survive. The study is rendered useful for teachers and scholars by an English translation of the text of the Déclaration, which enables the reader to see the illustrations through the eyes of a 15th century critic.