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If then there runs under the moon only a light air, not firm enough to bear a solid burthen, whereas under the earth there are, as Pindar says, columns and pillars of adamant for its support, therefore Pharnaces himself is out of all dread of the earth’s falling, but he pities the Ethiopians and those of Taprobane, who lie directly under the course of the moon, fearing lest so ponderous a mass should tumble upon their heads. And yet the moon has, for an help to preserve her from falling, her motion and the impetuosity of her revolution; as stones, pebbles, and other weights, put into slings, are kept from dropping out, whilst they are swung round, by the swiftness of their motion. For every body is carried according to its natural motion, unless it be diverted by some other intervening cause. Wherefore the moon does not move according to the motion of her weight, her inclination being stopped and hindered by the violence of a circular revolution. And perhaps there would be more reason to wonder, if the moon continued always immovable in the same place, as does the earth. But now the moon has a great cause to keep herself from tending hither downwards; but for the earth, which has no other motion, it is probable that it has also no other cause of its settlement but its own weight. For the earth is heavier than the moon, not only because it is greater, but also because the moon is rendered lighter by the heat and inflammation that is in it. In brief, it appears by what you say, if it is true that the moon is fire, that it stands in need of earth or some other matter, which it may rest on and cleave to, for the maintaining and nourishing of its power. For it is not possible to imagine how a fire can be preserved without some combustible matter. And you yourselves say that the earth continues firm without any basis or pedestal to support it.
