Still, I will descend to the task. Let the man who has placed such a 1 solid roof on the world tell me what reason there is for believing his statement that the heavens have such a thickness. What was it that took all these solid bodies up there and kept them there? Then, a firmament of such thickness must necessarily be of immense weight too. How is it that heavy bodies remain aloft? How is it that the huge mass does not come down and smash itself by its own weight? It is, I imagine, a 2 physical impossibility that such a vast weight as Artemidorus has brought to the support of the heavens should hang suspended, or be supported by a slight foundation. Nor can it be alleged that there are stays[93] of some kind outside by which it is prevented from falling. Nor again can there be any support in the centre[94] to receive and prop up the threatening mass. And again, no one will venture to assert that the universe is being constantly carried down through the immensities of space, falling all the time, though it is not evident that it falls, because its headlong course is to all eternity, having no final obstacle with which to collide. This is indeed a statement people have made about the earth, when they could discover no 3 explanation for a mass standing poised in air. It is borne down, say they, for ever; but it is not evident that it falls because the space into which it falls is endless. [93] The word is usually applied to a flexible fastening, hawser, cable, or the like. [94] Or, between the earth and it. Well, what argument[95] then justifies the assertion that it is not merely the five planets that move, but that there are many such in many quarters of the universe? Or if there is no probable proof of this, one may rejoin: What is there to prevent one from saying either that all the stars move or that none of them does? Besides, your argument 4 is in no way helped by that crowd of stars which you assume to be everywhere roaming about! For the more there are of them, the oftener will they meet with others; whereas comets are rare, and for that reason marvellous. And will not every age give evidence against you by noting and recording for the use of posterity the emergence of such stars? [95] The argument is resumed from the beginning of XIII. after the digression about the “firmament.” XV