But as I shall take occasion to consider this in a Critical Examination into the Nature, Uses and Advantages of Good Lungs, of which by it self, so I think fit to confine my present Observations to things more particularly concerning the Eye-sight. I was, you may be sure, not a little surprized, when being upon an Eminence I found my self capable by common Observation, to see and distinguish things at the distance of 100 Miles and more, and seeking some Information on this point, I was acquainted by the People, that there was a certain grave Philosopher hard by, that could give me a very good Account of things. It is not worth while to tell you this Man's Lunar Name, of whether he had a Name, or no; 'tis plain, 'twas a Man in the Moon; but all the Conference I had with him was very strange: At my first coming to him, he askt me if I came from the World in the Moon? I told him, no: At which he began to be angry, told me I Ly'd, he knew whence I came as well as I did; for he saw me all the way. I told him, I came to the World in the Moon, and began to be as surly as he. It was a long time before we could agree about it, he would have it, that I came down from the Moon; and I, that I came up to the Moon: From this, we came to Explications, Demonstrations, Spheres, Globes, Regions, Atmospheres, and a Thousand odd Diagrams, to make the thing out to one another. I insisted on my part, as that my Experiment qualified me to know, and challeng'd him to go back with me to prove it. He, like a true Philosopher, raised a Thousand Scruples, Conjectures, and Spherical Problems, to Confront me; and as for Demonstrations, he call'd 'em Fancies of my own. Thus we differ'd a great many ways; both of us were certain, and both uncertain; both right, and yet both directly contrary; how to reconcile this Jangle was very hard, till at last this Demonstration happen'd, the Moon as he call'd it, turning her blind-side upon us three Days after the Change, by which, with the help of his extraordinary Glasses, I that knew the Country, perceived that side the Sun lookt upon was all Moon, and the other was all world; and either I fancy'd I saw or else really saw all the lofty Towers of the Immense Cities of China: Upon this, and a little more Debate, we came to this Conclusion, and there the Old Man and I agreed, That they were both Moons and both Worlds, this a Moon to that, and that a Moon to this, like the Sun between two Looking-Glasses, and shone upon one another by Reflection, according to the oblique or direct Position of each other. This afforded us a great deal of Pleasure; for all the World covet to be found in the right, and are pleas'd when their Notions are acknowledg'd by their Antagonists: It also afforded us many very useful Speculations, such as these; 1. How easy it is for Men to fall out, and yet all sides to be in the right? 2. How Natural it is for Opinion to despise Demonstration? 3. How proper mutual Enquiry is to mutual Satisfaction?