Listens: big band

Feu follet

I recently watched Louis Malle's Le Feu Follet, which is marketed as The Fire Within for English-speaking audiences. I'm wondering about that translation.

For me, the fire within" would, in the English language, suggest an essential soul-spark, intended to be perceived as true and real. (We talk of someone "burning with faith" for example, or someone with a fiery spirit.)

Feu follet, however, seems to be French for "will-o'-the-wisp", which has connotations of insubstantiality and falseness. So it would seem that the English title is very nearly the opposite of its French meaning.

Also: I can only find the word "follet" occuring in the phrase "feu follet". Is it not in use as a "regular" word? It seemed like a peculiar French word to begin with, so I wouldn't be surprised if it were some archaic word that only survives in this one particular expression. I'm assuming it's etymologically related to "fou"...