A further particular feature of the Libro d’Ore Durazzo consists in its purple-tinted pages . This book of hours revives a tradition dating back to the times of the Roman Empire . In the city of Byzantium , too, the imperial offices made abundant use of purple codices with gold and silver lettering. In the West, during the early Middle Ages, the use of such materials was restricted to liturgical texts. Purple parchment was used for certain Greek codices from the area of Syria in the fifth and sixth centuries. An example is the Codex Purpureus Rossanensis conserved at Rossano Calabro ( Calabria , Italy ). The purple of these codices turns to a more violet colour over time.