This to any tolerable Optician, must be an evident Conviction of the Truth of the modern Astronomy, which now universally allow all those radiant Bodies the Stars to be of the same Nature with the Sun; and that as certainly they are no other than vast Globes of blazing Matter, all undoubtedly shining by their own native Light. But as you have often objected to what has been said of the Distance of the Stars in general, and may possibly from a Supposition, that they are, or may be, much nearer to us, infer, that their Light, like that of the Planets, may be also borrowed from the Sun, or from some other radiant Body, which, from the Nature of the Supposition, must of Consequence be invisible to us, I judge it will not be amiss to throw a few demonstrative Arguments in your Way, in order to lead you a little out of the Path of an early Prejudice, and draw you as it were by Degrees through the Dawn of astronomical Reasoning, out of your original Error, and rescue your Imagination from the false Notions imbibed from Phænomena only in your younger Years. This I guess cannot fail of reconciling you to this more rational Way of Thinking, and make you acquainted with Truths of much Consequence, which perhaps you have yet been an intire Stranger to. The grand _Deceptio Visus_, which I must first endeavour to remove, and which as a sort of Paradox in Nature, has, as I may say, imprisoned the Understanding of many superficial Reasoners, and in general all incurious Men, is this. Most People are too apt to think originally, that as the Heavens appear to be a vast concave Hemisphere, that the Stars must of course, as of Consequence, be fixed there, like so many radiant Studs of Fire, of various Magnitudes; and take it for granted, chiefly designed for no other Purpose than to deck and adorn the Canopy of our Night. This was long ago the Opinion of _Thales_ the _Milesian_, and wants not the Authority of many of the Antients to back it. Others, in particular [Q]_Ptolomy_ of _Pelusium_ in _Africa_, who from his Experience in this Science, is called by some the Prince of Astronomers, believed them to be Loop-holes in the vast solid celestial Firmament, emitting the Light of the Crystalline Heaven through it to all within it. The famous _Diogenes_, Cotemporary with _Plato_, conceived them to be of the Nature of Pumice-stones, and inclined to an Opinion, that they were the _Spiracula_, or Breathing-holes of Heaven. _Anaxagoras_ thought them Stones snatched up from the Earth by the Rapidity of its Motion, and set on Fire in the upper Regions above the Moon. [Footnote Q: _Ptolomy_ supposed two Heavens above that of the fixed Stars, which he called the eighth; _viz._ a ninth, the Crystalline, and a tenth the _Primum Mobile_. See Letter the second. The sacred Sun, above the Waters rais'd, Thro' Heav'ns eternal, brazen Portals blaz'd; And wide o'er Earth diffus'd his chearing Ray, To Gods and Men to give the golden Day.