De Maupassant uses a simile to describe Mathilde after she receives attention at the ball:
She danced, intoxicated, swept away, heady with pleasure, thinking of nothing, in the triumph of her beauty, in the glory of her conquest, in something like a cloud of happiness made of all that homage, all that admiration, all that awoken yearning, all that complete victory that is so dear to a woman’s heart.
This is a fitting simile for an experience that is ultimately insubstantial but still carries Mathilde far from the modest reality of her life. Just as a cloud is nothing but vapor—almost totally immaterial—so too is Mathilde’s attempt to become a high-society woman, based as it is in borrowed finery. The attention she receives from the men at the party is also ephemeral and fleeting in this way, since Mathilde is a married woman from the lower class, which means that none of their passing interest in her could ever amount to anything.
Notice the elements that make up this “cloud,” which are listed out individually and with great specificity: the cloud is made up of the “homage” and “admiration” of the crowd, but also the “yearning” and “victory” within Mathilde herself. This suggests that even Mathilde's goal of merely appearing to be a society woman is both superficial and tenuous at best; such is the gap between her and the other women at the ball. However, a closer look at this sentence reveals this shallow ambition to be dangerous in its import.
What's more, the tone of this scene feels strangely sinister. Mathilde is not gently borne away by her feelings, but “swept” away and “intoxicated” by the “heady” power of the mere suggestion of beauty and wealth. The appearance of wealth and the admiration of others has the potential to rob Mathilde of all self-awareness. Even if such things are superficial, then, they clearly hold enough sway over Mathilde to make her completely lose touch with reality.