Here is a book she might like;
Book Description: - During the Renaissance, artists traditionally encoded meanings into symbols, some of which drew upon a traditional repertoire available to educated people in the era. These hidden messageswhich ranged from the esoteric to the political to the religiouscould be communicated in everything from the position of a hand to the placement of the sun and moon Book Description
Thanks. I did ask her about it and she said that it was very common in all sorts of paintings, not just sacred ones. But she didn’t know all of the symbols. That book looks neat. It would make a great present. She loves those kinds of books on art history.