[Nymph Philosophy] Why the nude female form?

[Stefan Wirtz_2]

I think I saw astrological/astronomical diagrams in some manuscript with nude people in some sectors.  Unfortunately don't remember any details.

Maybe you mean this (ULIXBONENSIS, Roland, fl. 1430 Physionomia) or similar works:


(AG Jimenez will like this)

These figures look quite male.

Would nude figures be acceptable in illustrations of Greek legends? [..]

I would remind that such stuff had the tendency to be localized/regionalized and adapted to actual looks and fashions of the period it was reproduced. There are several occasions where ancient "classics" are reproduced in medieval gear and style -- so I do not recall many 14/15th Ct remakes of ancient greek nudity.