To be fair to the Greeks, thay also came up with the idea of elementary particles. I think it's Democritus who's credited with the idea of "atoms".

It's been ages since I've read about him in any depth but I remember something about him having an idea that because of the indefinite divisibility of length then the elementary particles would have to have a diameter smaller than any given length, i.e. be infinitesimal, so they had quite sophisticated speculations