Which is why I referred to philosophy instead of natural philosophy. ;)
Even so, many advanced concepts were present in Greek times. Heliocentrism, elements, atomic theory, etc. They even had napalm.
Of course, natural philosophy was to the ancients a particular focus of philosophy, and not a separate area of thinking.
Something that has fascinated me is the section of the Phaedo, recounting the death of Socrates, where he allows himself to digress in his very last moments into speculation concerning the nature of the globe of the earth. I's always been puzzling to me that these passages have been so little remarked upon, as they are fairly extensive.
He likens it to "one of those balls made of twelve pieces of skin", i.e. a dodecahedron, and each face is evidently its own "flat earth" isolated from the others. He speaks of each of these regions as having separate characters, and one is put in mind of Riverworld, or perhaps Flash Gordon, with its separate planetary realms.
I see it as an attempt, most probably by Plato as author, but maybe by Socrates himself, to reconcile the spherical earth taught by astronomy ( A Greek word! ) with the flat earth evident to our senses.