Manon is a classical nymph (oblique spoilers)
From Wikipedia:
"Nymphs are personifications of the creative and fostering activities of nature, most often identified with the life-giving outflow of springs ...
Nymphs tended to frequent areas distant from humans, but could be encountered by lone travellers outside the village, where their music might be heard, and the traveller could spy on their dancing or bathing in a stream or pool, either during the noon heat or in the middle of the night. They might appear in a whirlwind. Such encounters could be dangerous, bringing dumbness, besotted infatuation, madness or stroke to the unfortunate human. "
- Wikipedia
Also the whole structure is very reminiscient of Greek tragedy where an innocent mistake (a lost letter, in this case) in combination with human folly leads to downfall.