9. The differences from one another of the circles and the spheres in height are also given by Archimedes. He takes the perimeter of the Zodiac at 447,310,000 stadia, so that a straight line from the centre of the Earth to its extreme surface is the sixth part of the said number, and from the surface of the Earth on which we walk to the Zodiac is exactly one-sixth of the said number less 40,000 stadia which is the distance from the centre of the Earth to its surface. And from the circle of Kronos to the Earth, he says, the interval is 2,226,912,711 stadia; and from the [Sidenote: p. 71.] circle of the Fiery One to the Earth, 132,418,581; and from the Sun to the Earth, 121,604,454; from the Shining One to the Earth, 526,882,259; and from Aphrodite to the Earth, 50,815,160.[58] 10. And about the Moon we have before spoken. The distances and depths[59] of the spheres are thus given by Archimedes, but Hipparchus speaks differently about them, and Apollonius the mathematician differently again. But it is enough for us in following the Platonic theory to think of the intervals between the Wanderers as in ratios of 2 and 3. For thus is kept alive the theory of the harmonious construction of the universe in accordant ratios[60] by the same distances. But the numbers set out by Archimedes and the ratios quoted by the others concerning the distances, if they are not in accordant ratios, that is in those called by [Sidenote: p. 72.] Plato twofold and threefold, but are found to be outside the chords,[61] would not keep alive the theory of the harmonious construction of the universe. For it is neither probable nor possible that their distances should have no ratio to one another, that is, should be outside the chords and enharmonic scales. Except perhaps the Moon alone, from her waning and the shadows of the Earth, as to which planet alone you may trust Archimedes, that is to say for the distance of the Moon from the Earth. And it will be easy for those who accept this calculation to ascertain the number and the other distances according to the Platonic method by doubling and tripling as Plato demands.[62] If then, according to Archimedes, the Moon is distant from the Earth 5,544,130 stadia, it will be easy by increasing these numbers in ratios of 2 and 3 to find her distance from the rest by taking one fraction of the number of stadia by which the Moon is distant from the Earth.