The art of creating mosaic patterns grew and developed with the
rise of the Byzantine Empire in the 5th century. New
characteristics appeared in mosaics with Eastern influences in
style and the use of glass tesserae, known as smalti, sourced
from northern Italy. This added new texture and life to the
mosaic patterns being created, with the smalti, which were cut
from thick sheets of colored glass and had a rough surface and
tiny air bubbles throughout, being backed by reflective silver
or gold leaf. The application of mosaics also changed; while the
Romans favored the use of mosaic patterns for flooring, the
Byzantines took the art further and applied them to walls and
ceilings. They kept their smalti un-grouted to allow light to
reflect and refract through them and set their pieces at slight
angles to capture the play of light as it moved through the
space and allow the silver or gold backing to sparkle from every
angle. The mosaic patterns and themes melded together, with
Roman images being absorbed into th