My good friend Heather, knowing what a dork I am for symbols and mythology, found an amazing treasure for me at her library book sale: Dictionary of Subjects & Symbols in Art by James Hall. This puppy's out of print now, so it's such a treat to get my hands on it. I wish I'd had it when I was an art history minor in undergrad!
So, here's a wee sample:
Griffin: "a fabulous monster having the head, wings and claws of an eagle, and the body and hinder parts of a lion. Its origin probably lay in the ancient east where with other imaginary beasts it was said to guard the gold of India. The Greeks believed that griffins guarded the gold mines of the Scythians. It is a common bearing in heraldry where it symbolizes the combined qualities of eagle and lion - watchfulness and courage. As a Christian symbol it signifies the dual nature of Christ, divine (bird) and human (animal), and is a common motif in Gothic church sculpture. Dante describes the triumphal car of the Church drawn by a griffin."