But we are under a kind of Necessity to believe them either Suns or Planets, that is either dark or light Bodies; and since I have shewn the Improbability; nay, I may venture to say, the Impossibility of their being the first, it is natural sure to conclude, that they must be of the last Sort; and I am persuaded, if you but once consider how ridiculous it is to imagine so vast a Number of Bodies, all rolling round a Number of invisible Suns, which must otherwise be the Case, since they are seen on all Sides of ours, and cannot possibly be enlightened by him, or any, how all of them, by any one else, you cannot possibly have any sort of Difficulty in this Determination: But that no Arguments may be wanting to enforce your Belief of what is here concluded, it will not be amiss to put you in Mind of an optical Experiment or two, which cannot fail of convincing you of the vast Probability of what is here asserted of them; and next to a moral Certainty, demonstrate the Truth of what so many of the best Astronomers have advanced, as before namely, that the Stars are all, or most of them, Suns like ours. Place any concave Lense before your Eye, and you will find all visible Objects will appear through it, as removed to a much greater Distance than they really are at, and reciprocally as much diminished. Now, if you look upon one of these Glasses of a proper Concavity, opposed to the Sun or Moon, you will respectively have the Appearance of a real Star or Planet, the first exhibited by the Body of the Sun, the other by the Moon, and either more or less diminished in Proportion to the Surface of the Sphere the Glass is ground to. For Example, a double Concave, or Glass of a negative Focus, ground to a Sphere of about three Inches Diameter, will if opposed to the Sun's Disk at a proper Distance from the Eye, help you to a very good Idea how the Sun appears to the Planet _Jupiter_; and if a proper Regard be had to the Distance of the Planet _Saturn_, a Lense still more concave may be formed to give a just Idea of the Sun's Appearance to _Saturn_. Again, one much more concave than the former, proportioned to the Orbit of _Mars_, will naturally exhibit the solar Body, as seen from that Planet. To the Planet _Venus_ and _Mercury_, the Sun appearing much larger than to us at the Earth, to have any tolerable Notion of his varied Phænomena to them, it will be necessary to procure Glasses of a suitable Convexity, ground to reciprocal Concaves, which may easily be done to any Focus, so as to shew how the Sun, naturally appears to the Inhabitants of those two Planets.