2,600 years ago, Anaximander became the first person in recorded history to recognize that the earth exists as a solitary body which does not need to rest on top of anything else. Fascinated by the structure of the earth, he produced one of the first ever maps of the world. He did not restrict his thinking to astronomy and geography. He also theorized about evolution, concluding that life had first arisen in wet rather than dry conditions. He proposed that the first humans had been produced from fish.

Earth’s Place in the Universe

Anaximander had learned from Thales that the earth is a disk floating in an infinite ocean of water. Thales’ theory suggests that he had looked at the night sky and seen lots of bright disks. Describing the earth as a disk would therefore have seemed perfectly logical. Alternatively the disk idea might have come from the fact that the horizon, provided it’s unobstructed, is circular.

Anaximander modified Thales’ theory in a remarkably productive way. He completely discarded the ocean that Thales said supports the earth.

Earth Floats in the Center of the Infinite
Anaximander said there is nothing underneath the earth supporting it. He asserted that the earth floats in the center of infinity, held in position because it is an equal distance from all the other parts of the universe.

This is a strikingly sophisticated argument. More than 2,000 years before Newton’s law of gravity, Anaximander’s point of view seems to incorporate a subtle hint of Newtonian-style thinking, conceiving of a force of attraction between the earth and the planets and stars we see in the heavens.

Anaximander had made an immense conceptual leap. For the first time in history a human mind had grasped the idea that it is possible we live upon a mass that needs nothing below it.

It is difficult to overstate how important Anaximander’s revelation was for the future of astronomy and science. Without his insight, Aristarchus and (many years later) Nicolaus Copernicus could never have made the further intellectual leap needed to say that the earth orbits the sun.

How is the Universe Put Together?

Anaximander did not believe the universe he saw had always existed. He said it had grown from a seed – a primordial substance called Apeiron. The Apeiron was infinite and could not be created or destroyed. Everything we can sense in the universe had grown from it.

Tradition said that the sky was a solid hemisphere containing the heavenly bodies. It was supported above the earth by one of the Titans of Greek myths – Atlas.

Anaximander said that the heavenly bodies did not all lie on a single great celestial hemisphere. He placed the sun, the moon and the stars at different distances from Earth. However, after getting this right, he got the details wrong.

He imagined there were three rings of fire around earth – one for the sun, one for the moon, and one for the stars. The fires, he said, were enclosed in rings and hidden from us apart from holes that allowed their light through. The holes could change shape, which accounted for the moon’s phases. The holes could close, accounting for solar eclipses. The fire in the moon’s ring was cooler than the fire in the sun’s ring.

Although he correctly said the moon was closer to us that the sun, he incorrectly placed the stars closer to us than the moon.

To people today, Anaximander’s fire-rings look crazy. However, the fact that he imagined rings going all the way around Earth also allowed him to visualize an Earth that needed no support. So, despite the apparent craziness of his fire-rings idea, it led to a revolution in our understanding of the universe.