The migration waves of Byzantine Greek scholars and émigrés in the period following the Crusader sacking of Constantinople and the end of the Byzantine Empire in 1453 was a very welcome addition to the Latin texts scholars like Petrarch had found in monastic libraries for the revival of Greek literature and science via their greater familiarity with ancient greek works. They included Gemistus Pletho, George of Trebizond, Theodorus Gaza, and John Argyropoulos.