Anaxagoras · Philosophy
Anaxagoras declared the sun a vast incandescent rock, the moon an earth lit by reflected light, and the heavens made of the same stuff as the ground. For naturalising the gods of the sky, he was tried for impiety in Athens - the first martyr of free inquiry.
For the Greeks, the sun was Helios, a god who drove his blazing chariot across the sky; the moon was the goddess Selene; the heavenly bodies were divine, eternal, of a higher nature than earthly things. Anaxagoras shattered this picture with a single audacious claim: the sun is not a god at all, but a stone - an enormous mass of red-hot rock, glowing because it is heated to incandescence by the speed of its motion. It is, he said, larger than the entire Peloponnese. The moon, likewise, is an earthy body, with plains and mountains and ravines, which gives no light of its own but shines by reflecting the light of the sun. The stars are fiery stones, set ablaze by the cosmic rotation. The whole glittering, sacred dome of heaven is made, Anaxagoras insisted, of the same ordinary matter as the ground beneath our feet.
This was one of the most daring intellectual acts of the ancient world. Anaxagoras took the most awe-inspiring, most obviously ‘divine’ objects in human experience - the sun, the moon, the stars - and declared them to be mere matter, subject to the same natural explanation as stones and rivers. He continued the Milesian project of naturalism and pushed it into the heavens, the last refuge of the gods. If even the sun is just a glowing rock, then there is no region of the cosmos exempt from natural explanation, no sacred precinct where the gods rule untouchable. The universe is, top to bottom, a single natural order. It is hard, now, to feel how shocking and dangerous this was - but it was shocking enough to put him on trial for his life.
Anaxagoras’ claim that the heavens are made of stone received a spectacular apparent confirmation in his own lifetime. Around 467 BC, a large meteorite fell at Aegospotami, in the Greek world - a huge stone, blazing, that plunged from the sky to the earth. The ancient sources report that Anaxagoras was credited with having predicted it, or at least that the event was taken as dramatic evidence for his theory: here was a literal piece of the heavens, a glowing stone, fallen to earth - exactly what his cosmology said the heavenly bodies were. If stones can fall from the sky, then the sky contains stones; the heavenly bodies are not divine fire but rock, of the same nature as the meteorite now cooling on the ground.
This is the opening of the lesson. The rest — the dialogue, the primary source, and the recall — is in the app.
You learned that Anaxagoras held the sun to be a huge glowing stone (not a god), the moon to be earth-like and lit by reflected sunlight, and the heavenly bodies to be made of ordinary matter - for which he was prosecuted for impiety in Athens. Explain his naturalistic astronomy and why it was dangerous.
Leads to Socrates.
Begin this lesson →epoché — a humanities education that remembers you.