The development of our (i.e., we as humans) understanding and knowledge of the world around us has not been a straight line. In fact, some theories we take for granted as correct now, were actually posited centuries previously, eclipsed by other theories that we now dub ‘old’, naïve, and possibly even laughable. One such is the flat-earth theory. The notion that the earth was a sphere already existed in Antiquity.
Once, while showing a class of mine how the Romans perceived themselves as ‘Master of the Universe’ as it were, at the centre of their great empire, I flashed up an image of a coin from the Late Republic, which, on the reverse, showed the goddess Roma with her foot on the world, depicted as a globe. A sharply observant student, raised her hand and commented, ‘they thought the world was round, then?’ ‘Indeed, some clearly did. The Latin for earth, is, after all’ orbs terrarum (‘sphere of the lands’). I set her to do a little research of her own on ancient theories of a spherical earth. She was impressed and related in a later lesson what she had found, giving several examples. A fine early example is the Eratosthenes (born third century BCE). Firstly, he estimated the circumference of the earth with remarkable accuracy with a stick and observation of the angles of shadows. He arrived at almost the same figure that our satellites have confirmed. Variations in shadows in different places, but at similar times of day also led him to the notion that earth was spherical. Pythaogras, c.500 BCE and later Aristotle had also explored ideas of a spherical earth.
The incredible thought, exploration, and speculation of the great ancient thinkers deserve their place in the history of modern science and give a sobering lesson about the discontinuity of ideas in history. We are warned against being too self-congratulatory. They also attest both to the great potential of the human race. We can continue being amazing, whilst paying due reverence to the achievements of our ancient forefathers.