"Having enumerated some of the most remarkable Proprieties of Gravity, we come in the next place to consider what may be the Cause thereof. And first, I believe I shall not need to say much against the Opinion of Intelligent Matter, which supposes every part of Matter to act understandingly, for that being supposed, all Philosophy is vain, and there needs no farther Inquiry into Nature. And secondly, I have as little to say to its Cousin-german Opinion, viz. the Regimen of an Hylarchick Spirit. And 3ly, The Epicurean Atoms seem to me to give as little of Explanation almost as either of the former. And 4ly, For the Peripatetick Doctrine of tendency to the Center of the Universe, besides that the Foundation is false, the Earth being proved not to be in the Center, 'tis not yet understood what the tendency is. 5ly, The Cartesian Doctrine and that of Mr. Hobbs are both insufficient, because they do not give any reason why Bodies should descend towards the Center under or near the Poles. 6ly, Nor will the Magnetism of Gilbert or Kepler serve; for, as I shall afterwards shew, that is a Propriety distinct from Gravity, and of quite another nature."