The art that developped in the Eastern Roman Empire, also known quite incorrectly as Byzantine Empire, took on artistic forms far different from those that would later arise in the West.
If not all of its artistic production was religious, this nonetheless represents the most important Byzantine works, and what they have become famous for.
The artistic work was–and remains in the Orthodox Church–the embodiement of the divine, matter sanctified by the resurection.
Thus, looking at a work of art becomes a religious experience as it invites the viewer to meditate upon the subject represented.
https://www.youtube.com/watch?v=c2xF3Bk70NQ
