What is the theme in The Mysteries of Udolpho by Ann Ward Radcliffe?

Cruelty and indifference is another common theme in this novel, especially as it pertains to greed and mercenary motives. Mme. Cheron first disapproves of Valancourt because she believes him to be poor, but her opinion quickly changes when she learns that his aunt is Mme. Clairval. After Montoni marries Mme. Cheron, he refuses to allow Emily to marry Valancourt because he figures that he can sell her and earn a profit. He tries to do exactly that when he returns to Venice by agreeing to condone Count Morano's courtship for the fee of Emily's Gascony estates. Mme. Montoni also condones Count Morano's suit because of his title. Furthermore, M. Quesnel advises Emily to marry Count Morano because he wants the money and prestige associated with such an alliance.