You tell me you begin to be a tolerable good _Copernican_, and would now be glad to have my Opinion further upon the Nature of the Sun and Stars, with regard to the Suggestion of their being like Bodies of Fire. This you say will go a great Way towards confirming you in the Notion you have begun to embrace of a Plurality of Systems, and a much greater Multiplicity of Worlds than our little solar System can admit of. Besides, shewing in a very evident Light, that the Authorities cited in my first Letter are founded upon the clearest Reason. _Anaxagoras_, you say, believed the Sun to be a Lump of red-hot Iron; _Euripides_ thought it a Clod of Gold; and others still more ridiculously have imagined it to be a dark Body, void of all Heat. That the Sun is a vast Body of blazing Matter, notwithstanding the various Opinions of those primitive Sages, will, I think, hardly admit of a Question: Since the known Warmth of his prolifick Beams, and the visible Effect of the Burning-glass, puts it quite out of the Power of our present Set of Senses, at least to argue against it; and how reasonably we may imagine the Stars to be all of the same or like Nature, will sufficiently appear from these following Considerations: First, it is well known to all Mathematicians, that any visible Object of any determined Magnitude may be reduced to the Appearance of [P]a physical Point, by removing the Eye of the Observer to a proper or proportionable Distance from it, within the finite View: And that the apparent Diameter of every luminous celestial Body, will always be diminished reciprocally, in Proportion to the Distance from the Eye, till they become altogether imperceptible. [Footnote P: What is here meant by a physical Point, is a Point visible to the naked Eye, which human Art cannot divide; and so far it partakes of the Property of a mathematical one, which is only to be conceived, and not seen.] Thus the Disk of the Sun, which appears to us at Earth under an Angle of about half a Degree, if seen from the Planet _Saturn_, would appear not much bigger than the Planet _Venus_ or _Jupiter_, in their most neighbouring Vicinity does to us; and consequently to an Eye placed in the Aphelion Point of the Orbit of the great _Comet_ of 1680, his apparent Diameter would be so reduced as to seem but little bigger than the largest of the Stars; and by the same Analogy, or Way of Reasoning, admitting Space and Distance infinite, which I humbly apprehend is not to be disputed, were all the Matter in the Universe united, and conglobed in one Mass, with respect to ocular Sensation, it might be diminished so near to a mathematical Punctum, as to be almost adequate to our Ideas of Nothing.