He was able to regain control over Crete and Cyprus at the same time he was able to hold back First Bulgarian Empire's advances into his territory. His dynasty was thus able to maintain a period of peace under which economics, philosophy, art, and culture could thrive. This period produced a shift from the ban on the painting of religious figures to icons being painted to reflect the more classical and naturalistic influences of art on the culture. Mosaics such as the Virgin and Child in Hagia Sophia can still be seen today. The new style of art may have inspired Italian artists such as Cimabue and Giotto before the Italian Renaissance. The period also saw a proliferation of literature, such as "De Ceremoniis" ("The Book of Ceremonies"), which focused on governance, diplomatic interactions with neighboring nations, and other customs of the time. Education had also become a priority once again and the University of Constantinople boasted scholars such as Michael Psellus, who wrote the "Chronographia", a history of fourteen Byzantine rulers. Meanwhile, reforms in law sought to limit the power and growth of large land owners by the formation of trade guilds that allowed the state to control growth as described in the Book of the Eparch. The building Magnaura in Constantinople had already become a school in 849 and was headed by the philosopher Leo the Mathematician (c. 790 – after 869). Most of his works are lost.