Dante and the early astronomers . also the immense sphere of stars beyond,were all sweeping together at the same time in anopposite direction, and at the almost incredible paceof one revolution in a day. The brilliant idea occurredto him : Leave the stars at rest, let the seven planetsrevolve in their seven orbits, the nearer to the centrethe faster, and let earth herself revolve fastest of all,viz. in twenty-four hours, in the same direction. Ifshe keeps one face always turned towards the centre,like the moon, this will account quite as well for theapparent diurnal revolution of all the heave
Dante and the early astronomers . also the immense sphere of stars beyond,were all sweeping together at the same time in anopposite direction, and at the almost incredible paceof one revolution in a day. The brilliant idea occurredto him : Leave the stars at rest, let the seven planetsrevolve in their seven orbits, the nearer to the centrethe faster, and let earth herself revolve fastest of all,viz. in twenty-four hours, in the same direction. Ifshe keeps one face always turned towards the centre,like the moon, this will account quite as well for theapparent diurnal revolution of all the heavenly bodies,and the change of day and night on the earth. Philolaus did not make Earth remain stationary andsimply turn on her axis, which would have had justthe same effect on the apparent motions of the heavens;for it seemed more natural that she should revolve asdid the rest. The five naked-eye planets are allmentioned by name in his scheme. Was the centre, deprived of Earth, to be left empty ? PYTHAGORAS AND HIS FOLLOWERS. 71. Fig. 15. The Unirerse of Pythagoras, 72 PYTHAGORAS AND HIS FOLLOWERS. No, the centre was the Watch Tower of Zeus, the Hearthof the Universe, and here they placed the purestelement, fire. It was invisible to us, because we liveon the side of the earth-sphere turned away from thecentre; and also invisible to us was another planet,Antichthon, or Counter-Earth, for this revolved withinour orbit, and also in twenty-four hours. It was addedto the system, because the addition of Earth as aheavenly body spoiled the sacred number of seven,but by adding Antichthon, and counting the star-sphereas another, the total was brought up to ten, anothersacred number. The objection was made that, if Earth is moving inspace, this must bring about a change in the apparentsizes of sun and moon, as Earth is nearer or fartherfrom them, but the Pythagoreans were quite readyto believe that all the heavenly bodies are so distantthat this journey of Earth makes no difference to th
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