He was a leading authority on Byzantine art and history.
He became particularly interested in religious - and especially Byzantine - art.
For a brief time, one such source was Byzantine art.
There is also, on the west wall, some ancient Byzantine art.
They date back to about 1125 and are inspired by Byzantine art.
The subject matter of Byzantine art was primarily religious and imperial.
The painter also makes religious paintings inspired from the Byzantine art.
The work shows a humanity and tenderness new to Byzantine art in this period.
That explains why there is so little extant Byzantine religious art.
Diehl was the author of several influential books on Byzantine art and history.
Wörterbuch für Kunstbegriffe