'I would say, ‘That heavenly bodies do move on conic sections proves the inverse-square law.' But we are only speaking of fictions, so far. These proofs only apply to infinitesimal concentrations of mass, which do not exist in the real world. Real heavenly bodies possess geometry – they comprise a vast number of tiny particles arranged in the shape of a sphere. If Universal Gravitation exists, then each of the motes that make up the Earth attracts every other, and attracts the moon as well, and vice versa. And each of the moon's particles attracts the water in Earth's oceans to create tides. But how does the spherical geometry of a planet inform its gravity?'