What are the "eighteen methods of arranging Minerva's tresses"?

Question

In Jules Verne's Around the World in 80 Days, Jean Passepartout, Phileas Fogg's new servant, is introduced. We're given a description, which includes a descrption of his hair:

As for Jean, also known as Passepartout, he was a true Parisian of Paris. [...] His brown hair was somewhat tumbled; for while the ancient sculptors are said to have known eighteen methods of arranging Minerva's tresses, Passepartout was familiar with but one of fixing his own: three strokes of a large-tooth comb was enough to complete his morning rituals.
_{Around the World in 80 Days (1873) by Jules Verne, chapter II, translation by Jacqueline Rogers}

I'm not familiar with what "eighteen methods of arranging Minerva's tresses" that the ancient sculptors are said to have known might be. I'm familiar with Minerva is a figure in Roman mythology, but I'm not aware of anything special about her hair in particular or the ways in which it's carved. What is this referring to?

In addition, why is Passepartout being compared or equated to Minerva here? Minerva is the goddess of wisdom and strategy; is there some commentary being made here about Passepartout?

Answer 1

A quick Google and NGram search in English and French doesn't give any results about Minerva's tresses.

It's probably from the author's fancy, although the comment is surprising indeed as the narrator doesn't muse much into these poetic asides in the rest of the book.

It might just be meant as a contrast to the rest of the paragraph that describes Passepartout as a no-fuss, rough-and-ready man. In any case, he is not equated to Minerva - rather differentiated from her.