The Summary of Physics Restored

123Those also fall into a careless error who, seeing stones and certain heavy bodies sometimes generated in the air and cast down from it amid flashes, thunderbolts, and bursting clouds, have persuaded themselves that fire turns to stone and changes into earth, or that earth is carried up there. The matter stands quite otherwise. That hardened matter was never fire or earth, nor did it emerge from a sphere of fire, if such a sphere exists, or from the body of earth. Rather, an oily and viscous moisture, as though muddy, is enclosed in a cloud as in a furnace. Like a work of pottery, it is so seared and baked by the heat of burning exhalations that it becomes stone. Hence the hurled darts of the thunderbolt have been seen. Such meteors are swellings, congestions—in short, diseases of Nature, not elements. In a similar but slower way, a stone is generated from phlegm in the kidneys or bladder, sometimes in the stomach. For the microcosm too has its own meteors.