Nor is there any single theory, Certain and obvious, of how the sun Out of his summer stations passing forth Approaches the midwinter turning-point Of Capricorn, and how coming back thence He bends his course to the solstitial goal Of Cancer; then too how the moon is seen To traverse every month that space, whereon The journeying sun spends a year’s period. For these events, I say, no single cause Can be assigned. It seems most probable That the august opinion of Democritus Should be the truth; the nearer to the earth The several constellations move, the less Can they be borne on with the whirl of heaven: For in the lower portions of this whirl He says its speed and energy diminish And disappear; so that little by little The sun is outstripped by the signs that follow, Since he is far beneath the burning stars. And the moon, so he says, more than the sun. The lower and the further from the sky Her course is, and the nearer to the earth, The less can she keep even with the signs. For the more languid is the whirl whereby She is borne along, being lower than the sun, The more do all the signs around her path Overtake and pass by her. Thus it is That she seems to move backward to each sign More quickly, because the signs come up to her. It may be also that two streams of air Cross the sun’s path at fixed times, each in turn Flowing from opposite quarters of the world, Whereof the first may thrust the sun away Out of the summer signs, until he comes To his winter turning-point and the icy frost; While the other from the freezing shades of cold Sweeps him right back to the heat-laden regions And the torrid constellations. And just so We must suppose that the moon and the planets, Which roll in their huge orbits through huge years, May move on streams of air alternately From opposite quarters. Do you not also see How clouds are shifted by opposing winds, The lower in directions contrary To those above? Why should not yonder stars Be likewise carried by opposing currents Upon their mighty orbits through the sky? But night covers the earth with vast darkness Either when after his long course the sun Has entered on the uttermost parts of heaven, And now grown languid has breathed forth his fires, Exhausted by their journey, and worn out By traversing much air; or else because That same force which has borne his orb along Above the earth, compels him now to turn Backward his course and pass beneath the earth.