All stories and adaptations of those stories reflect the time in which they are made. When one is comparing Henry James's 1880 Washington Square with William Wyler's 1949 The Heiress, it becomes clear that they reflected a very different ethical code. This is most reflected in the character of Catherine Sloper, who in The Heiress is portrayed by Olivia de Havilland as stronger, but significantly more vengeful and bitter than she is in the original book. Two scenes reflect this change the best: the scene in which Dr. Sloper (Ralph Richardson) asks Catherine to promise to not take Morris (Montgomery Clift) back after he dies and the scene in which Catherine rejects Morris' plea to be allowed back.
In the book, Catherine's reaction to Dr. Sloper's demand is simply to tell him she cannot promise that. In truth, he has no right to make that demand of her. In the end he does basically disinherit her, and she is glad of it. It shows how bitter and domineering Dr. Sloper has been. Catherine has not deserved such treatment; and he had no right to make those demands of her; thus, her dignity in handling makes her look nobler. She does not care one about the money, so the threat of losing elicits no reaction from her.
In the movie Catherine attacks and criticizes Dr. Sloper quite harshly. Her badgering Dr. Sloper by insisting that she will certainly give Morris all his money shows a vindictive nature that is missing in the book. Dr. Sloper may deserve to be pilloried; but, in the end, it gains Catherine nothing.
A similar difference is shown in the scene in which Morris returns. In the book Catherine simply informs him she does not care and then goes back to her needlepoint. Now older, fatter, and balder, he is not even worth interrupting her pattern. In the movie she tricks the still trim and handsome Morris into thinking she is glad to see him, agrees to marry him that night, and then has the maid Maria (Vanessa Brown) lock him out when he returns to fetch her so he can experience what she had experienced when he stood her up.
Therefore, in the time between the writing of the book and the filming of the story, vengeance became a virtue. Displaying quiet dignity and turning the other cheek were no longer the ideal reaction for a heroine. With a female lead in the movies, it seems there is a fear of her not appearing strong enough to be a heroine. Catherine's reactions in the movie would fit in a John Wayne character. I find it a shame in a way because I think that, for either a male or female, the way Catherine handled herself was correct in the book; and I have a hard time thinking of a better way for her to have handled it. It is a shame that people started to feel that a hero/heroine had to indulge in equal retribution for every wrong to be a hero. Her responses in the book may not have perpetrated equal harm on her persecutors, but she thus showed unequivocally that she should not have been treated unjustly, and I cannot help but feel Dr. Sloper and Morris realized it and hence punished themselves.