Some time around the year 466 BCE – in the second year of the 78th Olympiad, the Roman naturalist Pliny the Elder tells us – a massive meteor blazed across the sky in broad daylight, crashing to the earth with an enormous explosion near the small Greek town of Aegospotami, or ‘Goat Rivers’, on the European side of the Hellespont in northeastern Greece. Pliny’s younger contemporary, the Greek biographer Plutarch, wrote that the locals still worshipped the scorched brownish metallic boulder, the size of a wagon-load, that was left after the explosion; it remained on display in Pliny and Plutarch’s time, five centuries later.
Both writers connect the meteorite with the Greek scientist Anaxagoras, who had a widely-known theory that heavenly bodies are made of the same sort of matter found on earth. The amazed Greeks took the stone as spectacular confirmation of this crazy idea, and Anaxagoras’s name would be linked to it forever afterward.
To get a better idea of this meteorite’s figurative impact, consider a parallel from closer to our own time. Albert Einstein published his general theory of relativity in 1915, a decade after the narrower special theory of relativity had established a secure scientific reputation for him, along with other important papers he published in 1905, his annus mirabilis. Few physicists could follow the ins and outs of general relativity, and its immediate influence was slight. But one of those few was Arthur Eddington, whose widely publicised 1919 observations of a solar eclipse appeared to confirm Einstein’s revolutionary prediction that gravity bends light. ‘LIGHTS ALL ASKEW IN THE HEAVENS’ ran the delightful headline in The New York Times. ‘Men of Science More or Less Agog Over Results of Eclipse Observations. EINSTEIN THEORY TRIUMPHS.’ Overnight, Einstein’s name became synonymous with genius; two years later he won a Nobel Prize.
If we took that level of agog and multiplied it hundredfold, we might begin to approach the shockwave of the Aegospotami meteorite – and its effect on Anaxagoras’s reputation. For one thing, revolutionary as it was, Einstein’s improvement on Newton was subtle, not only in being hard to grasp but also in the sense that the effects Einstein predicted will never be perceptible to normal people under normal circumstances. Anaxagoras’s ‘general theory’ of the heavens completely shattered normal circumstances. The sky would never be the same.
For a modern person, grasping Anaxagoras’s audacity takes some doing, but it will help to recall that the chief organ of sight is not the eye but the brain. In other words, it’s our brains, not our eyes, that tell us what we’re looking at. When people in the ancient world looked up at the night sky, like us they saw lights. But that’s where the shared experience stops. Our brains tell us most of those lights are distant suns, and a handful of others are floating spheres in orbit around our sun, like the earth. Their brains told them all those lights were gods or mythical creatures. The idea that they might be objects floating in space didn’t exist yet. We look at the sun and see a giant ball of hydrogen converting itself into helium through a process of nuclear fusion; an ancient Greek saw the god Helios, driving a blazing chariot. We look at the moon and see a cold, airless, dusty ball of rock partly lit by the sun; an ancient Greek saw the goddess Selene, aglow with her own soft luminosity. The cosmos was alive, brimming with gods and goddesses, and their movements were omens. A basically well-ordered place – the Greek word cosmos originally meant “order” – its stability was nonetheless always under threat by the unruly. It quivered with agency and import, and it was all connected in an organic whole, from great to small alike.
The first to split this seamless cosmos was Thales, who lived perhaps just over a century before Anaxagoras, in the region of coastal Anatolia (modern Turkey) known to the Greeks as Ionia. Ionia’s principal city was the fabulous trading port of Miletus, where Thales was from, so he is known to history as Thales of Miletus. If the Greek world were a quiet pond and we threw a stone representing ‘the tradition of free rational inquiry’ into it, Miletus would be the site of the splash. From there, the waves spread outward within a few generations. Thales had students, his students had students, those students had their own students, and so on. Thales and his successors recognised that there’s a real world out there, that it’s governed by orderly operations of its own, and that we don’t need gods or spirits to explain how those operations work. They cracked the world in two parts, natural and supernatural, and in doing so they pushed the supernatural off to one side. Together, they are the first scientists. And, yes, they made waves.
The achievements of these early scientists have long been dismissed by scholars, largely because, with the benefit of hindsight, they seem so basic. And it’s true that compared with the rapid progress Greek science made starting a bit later, in Plato and Aristotle’s time, those contributions might well appear trifling. Not to mention compared with today. Yet science had to start somewhere. A more accurate assessment might judge them not against what came after, but against what came before. From this perspective, these earliest insights were astonishing and unparalleled, as Daniel Graham, a classicist and historian of science at Brigham Young University, has now demonstrated in his authoritative 2013 book Science Before Socrates.
Graham paints a new picture of early science that gives central roles to Anaxagoras and his perhaps slightly older contemporary, Parmenides. Both could trace their intellectual ancestry back to Thales through teacher-student relationships. While invoking natural causes for things, Thales had stuck to the conventional view that the earth is a flat plate supported by something. As far as we know, the intuitive idea of a flat earth was common to all cultures the world over, though the supporting arrangement runs the gamut from turtles for the Maya to pillars for the Hebrews to elephants for the Indians. Thales’s student Anaximander was the first to propose the earth as an object floating in space. According to him, it was shaped something like a bongo drum, with a flat surface at either end. The sky was generally seen as a dome or vault above the flat earth, across which the sun, moon, planets and stars moved or were pulled in regular patterns. One of Anaximander’s students, Xenophanes, envisaged a sort of grid universe in which the earth is an infinite plane with numerous suns and moons crossing it in straight lines. Another thinker, Heraclitus (of not-being-able-to-step-in-the-same-river-twice fame), claimed the moon is a bowl of fire. He, too, thought we get a new sun every day – the size of a human foot. It’s understandable that modern scholars might dismiss such notions as wildly speculative and ungrounded in empirical observation.
Not so fast, says Daniel Graham. Even Heraclitus had worked out his fiery bowl theory of the moon so that it agreed with the observable lunar phases. What makes his theory feel out of touch to us is not so much the bowl part (after all, why not?) as the part where the moon is giving off its own light. That was the universal belief at the time, however, and not senseless at all, but common sense.
This is where Parmenides comes in, a student of Xenophanes from the Greek colony of Elea in southern Italy. Long understood only as a feverish theoriser caught up with abstruse questions of being and nothingness (which, admittedly, he was), Parmenides is also revealed by Graham’s careful research to have been a hard-headed empirical astronomer. For it was he who figured out that the moon gets its light from the sun, an insight now so pervasive as to be entirely taken for granted by little children. Yet there it is for the first time in the few surviving scraps of Parmenides’s poem On Nature, in which he strikingly describes the moon as ‘a lamp by night, wandering around the earth with borrowed light’ and ‘ever gazing toward the rays of the sun’. That second part suggests how Parmenides worked: by methodically observing lunar phases, and noticing what Heraclitus had not – that the bright part of the moon always faces the sun. Before Parmenides, other theorists, like Heraclitus, all portray the moon as generating its own light; after him, they all understand that moonlight is actually reflected sunlight. Heliophotism, this idea has been dubbed recently, in the way scientists still like to use Greek. Or, in English, ‘sunlightism’. It is arguably the first genuine scientific discovery, and quite possibly the most productive. Much else would be illuminated by it.
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