MYST. It is difficult to determine their number because of the variety of opinions among the authorities, each differing from the other, and because of the inadequacy of the proofs of such things. For Eudoxus has stated that the spheres with their deferents are not more than three and twenty in number. Calippus has put it at thirty, and Aristotle[452] at forty-seven, which Alexander Aphrodisiensis[453] has amended by adding to it two more on the advice of Sosigenes. Ptolemy holds that there are 31 celestial spheres not including the bodies of the planets. Johan Regiomontanus says 33, an opinion which is followed by nearly all, because in the time of Ptolemy they did not yet know that the eighth sphere and all the succeeding ones are carried around by the movement of the trepidation. Thus he held that the moon has five orbits, Mercury six, Venus, Mars, Jupiter, and Saturn each four, aside from the bodies of the planets themselves, for beyond these are still the spheres and deferents of the eighth and ninth spheres. But Copernicus, reviving Eudoxus' idea, held that the earth moved around the motionless sun; and he has also removed the epicycles with the result that he has greatly reduced their number, so that one can scarcely find eight spheres remaining. [Footnote 452: Metaphy. XII.] [Footnote 453: In his commentaries on Book XII of Metaph. where he gives the opinion of Calippus and Eudoxus.] THEO. What should one do with such a variety of opinions? MYST. Have recourse to the sacred fountain of the Hebrews to search out the mysteries of a thing so deeply hidden from man; for from them we may obtain an absolutely certain decision. The Tabernacle which the great Lawgiver Moses ordered to be made[454] was like the Archetype of the universe, with its ten curtains placed around it each decorated with the figures of cherubim thus representing the ten heavens with the beauty of their resplendent stars. And even though Aben-Ezra did not know of the movement of trepidation, nevertheless he interpreted this passage, "The heavens are the work of Thy fingers" as indicating the number of the ten celestial spheres. The Pythagoreans seem also to have agreed upon the same number since, besides the earth and the eight heavens, they imagine a sphere Anticthon because they did not then clearly understand the celestial movements. They thought however, all should be embraced in the tenth. [Footnote 454: Ex. XVIII and following. Philo Judæus in the Allegories.] THEO. The authority of such writers has indeed so great weight with me that I place their statements far in advance of the arguments of all others. Nevertheless if it can be done, I should wish to have this illustrated and confirmed by argument in order to satisfy those who believe nothing except on absolute proof.