Or what if beyond ſuch a determinate Space he has left an infinite Vacuum; to ſhow, how inconſiderable all that he has made is, to what his Power could, had he ſo pleas’d, have produced? But I am falling, before I am aware, into that intricate Diſpute of Infinity: Therefore I ſhall wave this, and not, as ſoon as I am free of one, take upon me another difficult Task. All that I ſhall do more is to add ſomewhat of my Opinion concerning the whole World, as it is a Place for the Reception of the Suns or fix’d Stars, every one of which, I have ſhowed, may have their Planetary Syſtems about them. [Every Sun has a Vortex round it, very different from thoſe of Cartes.] I am of Opinion then that every Sun is ſurrounded with a Whirl-pool or Vortex of Matter in a very ſwift Motion; tho’ not in the leaſt like Cartes’s either in their Bulk, or manner of Motion. For Cartes makes his ſo large, as every one of them to touch all the others round them, in a flat Surface, juſt as you have ſeen the Bladders that Boys blow up in Soap-ſuds do; and would have the whole Vortex to move round the ſame way. But the Angles of every Vortex will be no ſmall hindrance to ſuch a Motion. Then the whole Matter moving round at once, upon the Axis as it were of a Cylinder, did not a little puzzle him in giving Reaſons for the Roundneſs of the Sun: which however they may ſatisfy ſome People that do not conſider them, really prove nothing of the Matter. In this æthereal Matter the Planets float, and are carried round by its Motion: and the thing that keeps them in their own Orbs is, that they themſelves, and the Matter in which they ſwim, equally ſtrive to fly off from the Center of this Motion. Againſt all which there are many Aſtronomical Objections, ſome of which I touch’d upon in my Eſſay of the Cauſes of Gravity. Where I gave another Account of the Planets not deſerting their own Orbs; which is their Gravitation towards the Sun. I ſhow’d there the Cauſes of that Gravitation, and cannot but wonder that Cartes, the firſt Man that ever began to talk reaſonably of that Matter, ſhould never meddle with, or light on it. Plutarch in his Book of the Moon above-mentioned ſays, that ſome of the Ancients were of Opinion, that the Reaſon of the Moon’s keeping her Orbit was, that the Force of her Circular Motion was exactly equal to her Gravity, the one of which pull’d her to, as much as the other forc’d off from the Centre. And in our Age Alphonſus Borellus, who was of this ſame Opinion in the other Planets as well as the Moon, makes the Gravitation of the primary Planets to be towards the Sun, as that of the Secondary is towards the Planets round which they move: Which Sir Iſaac Newton has more fully explain’d, with a great deal of Pains and Subtilty; and how from that Cauſe proceeds the Ellipticity of the Orbs of the Planets, found out by Kepler. According to my Notion of the Gravitation of the Planets to the Sun, the Matter of his Vortex muſt not at all move the