  The year 1277 marked a turning-point in his career: Giles was involved in the condemnation of the heterodox Aristotelianism issued by the Parisian bishop Etienne Tempier, although the process against him must be distinguished from the famous decree of the 7 of March 1277, as Robert Wielockx has shown. After 1277 Giles must have abandoned Paris, but his presence is attested in Italy not earlier than 1281. Before leaving Paris he completed his De regimine principum, which is dedicated to the young Philip, the future Philip the Fair.