XIII
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In reply to arguments like mine it is urged by Artemidorus that the five planets are not the only stars with erratic courses, but merely the only ones of the class that have been observed. But innumerable others revolve in secret, unknown to us either by reason of the faintness of their light, or the situation of their orbit being such that they become visible only when they reach its extremities. It is thus, he says, that certain new stars enter our field of vision, mingling their light with the fixed stars, but displaying a brightness greater than is usual in stars. This is the least serious of his lies: his account of the universe is from end to end a shameless tissue of lies. For instance, if we are to believe him, the upper regions of heaven are perfectly solid—a lofty thick vault, as hard as the roof of a house, formed by the accumulation of masses of atoms. The surface immediately above it is of fire so compact that it cannot be broken up or altered. Nevertheless, it has certain ventilators, and, as it were, windows through which portions of the fire stream from the outer part of the universe, but not so large as to cause commotion in the inner; and again the fires pass from the world back into the outer spaces. These extraordinary appearances, therefore, Artemidorus supposes, have streamed in from that mass of matter which lies outside the world. To set about disproving such a theory is nothing short of beating the air for the sake of exercising the muscles!