"The fact, however, is certain, that at some remote period there were mathematicians and astronomers who knew that the sun is in the centre of the planetary system, and that the earth, itself a planet, revolves round the central fire;--who calculated, or like ourselves attempted to calculate, the return of comets, and who knew that these bodies move in elliptic orbits, immensely elongated, having the sun in one of their foci;--who indicated the number of the solar years contained in the great cycle, by multiplying a period (variously called in the Zend, the Sanscrit, and the Chinese ven, van, and phen) of 180 years by another period of 144 years;--who reckoned the sun's distance from the earth at 800,000,000 of Olympic stadia; and who must, therefore, have taken the parallax of that luminary by a method, not only much more perfect than that said to be invented by Hipparchus, but little inferior in exactness to that now in use among the moderns;--who could scarcely have made a mere guess when they fixed the moon's distance from its primary planet at fifty-nine semi-diameters of the earth;--who had measured the circumference of our globe with so much exactness that their calculation only differed by a few feet from that made by our modern geometricians;--who held that the moon and the other planets were worlds like our own, and that the moon was diversified by mountains and valleys and seas;--who asserted that there was yet a planet which revolved round the sun, beyond the orbit of Saturn;--who reckoned the planets to be sixteen in number;--and who reckoned the length of the tropical year within three minutes of the true time; nor, indeed, were they wrong at all, if a tradition mentioned by Plutarch be correct."(64) 64) Drummond, On the Zodiacs, p. 36.