What are the motifs in Borrower of the Night by Elizabeth Peters?

Competition is a recurring idea in the book. Vicki Bliss is the main character in the story and she obviously feels competitive toward most of the people in the story. While her competition is not physical, it is plainly stated that she believes herself to be superior to men in general but cannot be taken seriously because of her good looks. While there seems to be an unspoken competition between Vicki and Tony almost from the beginning of the book, it is verbally stated and put out in the open when they decide to both go looking for the Riemenschneider piece.