thinking outside the box

Three men - Erastosthenes, Aristarchus, and Anaxagoras – were responsible for first calculating to within a fairly decent precision (5-15% error), the diameter of the earth, moon, and sun as well as the distance the latter two were from the earth. And clearly in doing this also deduced that all three were spheres. All three were Greeks. This was all done near the changeover from B.C. to A.D.

Now consider these facts:

1. This was done without the aid of calculators or any kind of reliable scientific measuring instruments
2. This was done some 1500 years before Galileo & Copernicus started espousing beliefs about the earth being spherical
3. They never had the benefit of being educated on any formal scientific theory or scientific method
4. Before this leap of logic the Greeks made, all prior civilizations had resorted to Gods or spiritual mechanisms for the movement and descriptions of the three celestial satellites
5. There was still heretical persecution going on at the time for beliefs which stepped outside the spiritual explanations many had given previously