What is the moral of the story in The Necklace by Guy de Maupassant?
There are a number of different morals one could derive from "The Necklace." It's just one of the reasons why it's such a fascinating story. First of all, and perhaps most obviously, the story teaches us that material things cannot bring happiness. Wearing what she thinks is a valuable necklace, Mathilde feels like the belle of the Education Ministry ball. But her happiness doesn't last for very long, and indeed her shallowness and obsession with material objects leads to great unhappiness. "All that glitters is not gold" is an appropriate description both of the fake necklace and the high society life that Mathilde briefly tastes and to which she desperately aspires.
Related to the first point is the theme of class snobbery. Mathilde acts like she has noble blood coursing through her veins, despite her lower middle-class status. And it's Mathilde's desire for social climbing that ultimately leads to her undoing. The moral appears to be that class is something you're born with, not something to which you can, or should, aspire. Wanting so badly to be a member of a supposedly higher social class means that you're trying to be something and someone you're not. This doesn't necessarily mean that people shouldn't try to improve their position in life; but what it does mean is that they should remain true to themselves, instead of engaging in fantasies and delusions, imagining themselves to be different than they really are.
The moral (or theme) of "The Necklace" by Guy de Maupassant depends on your view of the short story. For instance, we early on learn that Mathilde longs to be a part of the upper class. All she wants is to go to the party and have a great time. When her dream comes true, reality leaves her crushed when she realizes that she lost Jeanne's necklace. Instead of beginning a life of grandeur in the upper class, Mathilde plummets all the way to the lower class as she has to work harder to make up for the loss of the necklace. This theme would be an example of man versus society - or the conflict between classes within a society.
Another potential theme maybe the conflict between generosity and greed. Who is generous in the story? Mathilde so longs to be a part of the upper class that she covets what she does not have. Even though she has more than some (one servent) she wants more and more. This is a sign of greed. Contrast that with her husband's selfless act of giving up what he wants (the hunting trip) in order to make sure that Mathilde gets her dream. Even Jeanne is generous in allowing her friend to use the necklace for her special night. By the end of the story, we can see the moral of the story for this view is to be careful what you wish for because the grass always looks greener on the other side, but reality will prevail.