In some Measure to convince you that I have committed no Error in this, I will try by some less mathematical Method than that of meer Numbers, to imprint an Idea in your Mind of the true Extent of the solar System, and the Magnitude of all its moving Bodies, by natural Objects most familiar to your Senses. When we endeavour to form any Idea of Distance, Magnitude, or Duration, by Numbers only, we so soon exceed the Limits of Conception, that this way we find our Faculties of reasoning as finite as our Senses; and no doubt 'tis right it should be so, Providence, as it were, having ordain'd that the first should only attend the last, in such an adequate Degree to a determin'd Distance; but what Distance or Degree of Knowledge is destin'd to human Nature, none but the Power that gave it can tell. 'Tis certain that beyond the third or fourth Place of our Nomenclator, we receive but very faint Impressions of the thing exprest, and can frame scarce any Notion at all of either Number, Distance, or Magnitude, signified beyond it: Hence Astronomers are frequently oblig'd to have recourse to mixt Ideas, and make Things of different Natures and Properties assist each other, to excite more adequate Ideas of what they would have conceived. Thus to express immense Distances and Magnitude, they frequently apply themselves to Time and Motion; and _vice versa_, to signify a long Duration, they have often recourse to Distance and Matter, removing, in Imagination, Worlds of Sand, Grain after Grain, to some remote known Region. _Hesiod_,[AQ] to express his Idea of the Distance from his highest Heaven to Earth, and from Earth to Hell, or _Tartarus_, supposes an Anvil to be let fall from one to the other, which he says in nine natural Days would reach the Earth from Heaven, and in the same time would fall from the Earth to Hell. [AR]_Homer_ makes his _Vulcan_ fall from Heaven to the Island of _Lemnos_ in much less Time, not exceeding one full artificial Day. [Footnote AQ: From the high Heaven a brazen Anvil cast, Nine Nights and Days in rapid Whirls would last, And reach the Earth the Tenth, whence strongly hurl'd; The same the Passage to th' infernal World. Cooke. ] [Footnote AR: Hurl'd headlong downward from th' etherial Height; Toss'd all the Day in rapid Circles round, Nor till the Sun descended touch'd the Ground. Pope. ]