Although my career has little if anything to do with it, one of my BA's is in Art History, and my primary hobby is calligraphy/manuscript illumination. An essential element to virtually all Christian art, especially in the Byzantine and Roman traditions, is the symbology or iconography and what was basically a visual vocabulary for the generally illiterate masses. A good introduction to the overwhelmingly obvious, as well as some of the more esoteric imagery used is George Ferguson's Signs and Symbols of Christian Art.
Thank you so very much. I will certainly pick this up. Sounds also as though you have a lovely and fulfilling hobby as well. :-)