Plato apparently had a rudimentary knowledge of precession, the slow wobble of the earth’s axis, which would cycle once in 25,920 years, what Plato called the Great Year, and because he wrote that the earth is a sphere within a sphere, he had the essential knowledge to know that the ancient greek measuring unit, the foot metric (12.16 modern inches), is surely an earth commensurate measure; a reduction of the circumference of the earth by a factor of 6,000 greek feet per nautical mile x 21,600 nautical miles = 129,600,000 greek feet which compose the circumference length of the earth.
The egyptian royal cubit was also earth commensurate, also a subdivision of the nautical mile, and the dimensions of the Great Pyramid leave the fingerprint of how they measured the earth, by the rate of precession, see article #2 at http://IceAgeCivilizations.com to understand how the ancients measured time, not solar transit time, but precession time, to accurately measure east-west distances, thought not possible until the 1750’s with the invention of Harrison’s Chronometer, but the ancients could measure the much slower rate of precession in order to accurately measure time by apparent star movements, not by the apparent movement of the sun. (Actually, the earth’s rotation and wobble cause the stars to appear to move.)
The 12 constellations of the zodiac appear to move clockwise through the course of a year as they “rise” in the darkening evening skies, because of the counterclockwise rotation of the earth around the sun, but because of the very slow clockwise wobble of the earth’s axis, 72 years/degree, the stars will appear slightly to the left from where they were, exactly one year previously, like a ratchet, so the constellations circle (so to speak) the horizon during the course of a precession cycle, the slow wobble of the earth’s axis, once in 25,920 years, and this is the “changing of the houses of the zodiac,” every 2,160 years; 25,920 divided by 12 houses.
Astrology predicts the future positions of stars, short term, by the rate of the earth’s transit around the sun, and long term, by the rate of precession, that which the ancients used to measure the earth as explained in the link above, so earth locations were measured by the present and accurately predicted future positions of the stars, falling in line with Plato’s notion that the earth is a sphere within the celestial sphere, but since Eratosthenes (centuries after Plato) is thought to have been the first to roughly calculate the circumference of the earth, by a crude system of shadows, allowing only 5% accuracy, whereas the precession method allowed 0.5% accuracy, so he obviously was ignorant of the evidence for accurate earth measure, geo metry.
And see http://genesisveracityfoundation.com.