I have the following passage, written by Émilie du Châtelet in 1738:
Il me paroît que le Lecteur est un peu étonné de se trouver tout d'un coup dans la question la plus difficile de l'optique, pour la solution de laquelle il ne faut pas moins que la Métaphysique la plus recherchée.
I believe I understand the meaning but would like to check because "il faut" constructions are always throwing me off. According to this post, it seems that the "pas moins" is an addition made for emphasis that doesn't actually change the meaning; the "pas" goes with "moins," not with "ne." In other words, saying "il ne faut que la Métaphysique" would mean the same thing.
My translation would be something like, "the solution of which requires the most thoroughly investigated metaphysics," or more colloquially, "which only the most thorougly investigated metaphysics could resolve."
I appreciate any thoughts about this construction or my translation.