Better known is the "De mensura Orbis terrae", a summary of geography, giving concise information about various lands. This work was based upon a "Mensuratio orbis" prepared by order of Emperor Theodosius II (AD 435), a manuscript copy of which was possessed by the Carolingian court. Godescalc had already made use of this copy (781-783) for the composition of his celebrated "Evangelistarium". Dicuil uses Pliny the Elder, Gaius Julius Solinus, Paulus Orosius, Isidore of Seville, and other authors, and adds the results of his own investigations.