The Question and Answer section for The Necklace is a great resource to ask questions, find answers, and discuss the novel.
Madame Loisel doesn't simply want to be a part of the upper class, she believes she was born to be there. Mathile thinks that she is entitled to wealth and has been cheated.
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In order to pay for the replacement necklace, M. Loisel uses his inheritance, eighteen thousand francs) and borrows the rest. He then had to work endless hours and take a smaller flat.... a less expensive flat to pay back the debt he incurred....