Horologium Olomoucense is a collectarium (liturgical book of collects or prayers) that is recited during the Divine Office at horae (specific times) during the day. The manuscript was written for the cathedral chapter in Olomouc in the southern part of the present-day Czech Republic before the year 1150. A famous image depicting Pope Gregory I (circa 540–604) is found at the beginning of the liturgical texts. The pope is on a throne and dictating to his friend and pupil, Petrus Diaconus, who is sitting at his feet. He is surrounded by a large number of religious and secular people, including Henricus Episcopus and Bishop Jindřich (Henricus) Zdík (circa 1080–1150), an important figure in the history of the medieval cathedral in Olomouc. The manuscript’s scribe and illuminator are depicted at the bottom margin. The scribe is a monk who is described by a partially eroded initial R. He is seen as being helped by the illuminators Hildebertus Pictor and his apprentice Everwinus. The miniature illustrates well the cooperation that gradually developed during the 1100s between the monks and the illuminators. Horologium Olomoucense came to Sweden as war booty during the Thirty Years War (1618–48).