Anaximander was one of the world’s first scientists and had some amazingly modern theories, as Carlo Rovelli reveals

When Anaximander was born in Miletus in 610 BCE, the Golden Age of Greek civilization, the time of Pericles and Plato, was still nearly 200 years in the future. Tarquin the Elder, according to tradition, reigned in Rome. At around the same time, the Celts founded Milan, and Greek settlers from Anaximander’s Ionia founded Marseille. Homer… had composed the Iliad two centuries earlier, and Hesiod had already composed the Works and Days, but none of the other Greeks’ illustrious poets, philosophers, and dramatists had begun writing. Sappho, still a girl, was living on an island near Miletus …

Anaximander wrote a treatise in prose, On Nature (Περι ́ φυ ́σεως), now lost. Only one fragment remains, quoted by Simplicius of Cilicia in his commentary on Aristotle’s Physics… Much has been written about this handful of obscure words, which can easily inspire fanciful interpretations. It is always difficult to interpret a passage out of its context with any degree of certainty. It is not this fragment of direct evidence that tells us what is interesting in Anaximander’s ideas. Instead, many Greek sources relay the content of Anaximander’s book…

Here is a likely summary of the content of Anaximander’s On Nature:

1. The transformation of one thing into another is regulated by “necessity,” which determines how phenomena unfold in time.

2. The multiplicity of things that constitutes nature derives from a single origin or principle, called the apeiron (απειρον), the “indefinite” or “infinite.”

3. The world came into being when hot and cold separated from the apeiron. This separation generated the cosmic order. A ball of flame grew around the air and the Earth “like the bark of a tree.” This ball then broke apart and was confined inside the wheels that form the Sun, the Moon, and the stars. The Earth was originally covered in water, which slowly dried up.

4. The Earth is a body of finite dimensions floating in space. It doesn’t fall because there is no particular direction toward which it might fall. It is “dominated by no other body.”

5. The Sun, the Moon, and the stars rotate around the Earth, forming complete circles. Immense wheels, similar to wagon wheels, carry them along. They are hollow inside (like a bicycle tire), filled with fire, and pierced along their inward-facing surface. The Sun, the Moon, and the stars that we see in the sky are the fire visible through these holes. The wheels are probably meant to explain why the planets don’t fall. The stars are on the wheels closest to us, the Moon on the middle wheel, and the Sun on the wheel farthest from us. Their distances from Earth are in the proportion 9:18:27.

6. Meteorological phenomena have natural causes. Rainwater is water from the sea and rivers that evaporates because of the Sun’s heat. It is carried away by the wind and then falls onto the Earth. Thunder and lightning are caused by colliding and splitting clouds. Earthquakes are caused by fissures in the Earth brought about, for example, by excessive heat or rain.

7. All animals originally came from the sea or from the primal humidity that once covered the Earth. The first animals were thus either fish or fishlike creatures. They moved on to land when the Earth became dry, and they adapted to living there. Human beings, in particular, cannot have been born in their current form, because babies are not self-sufficient, so someone else had to have fed them. They grew out of fishlike creatures.

To these theories we can add the following points:

8. Anaximander drew up the first map of the known world. In the generation following him, another Milesian, Hecataeus, expanded this map. Hecataeus’s map served then as the basis for all other ancient (and hence modern) maps.

9. Anaximander wrote the first text in prose about natural phenomena. Earlier works on the origin and structure of the world (Hesiod’s Theogony, for example) had always been written in verse.

10. Anaximander is traditionally credited with introducing the use of the gnomon to the Greek world, perhaps from Babylonia. A gnomon is a rod set vertically in the ground. By measuring the length of the shadow it casts, one can determine the Sun’s altitude. A complex astronomy of the Sun’s movements can be developed using a gnomon.

11. Some authors report that Anaximander was the first to measure the obliquity of the ecliptic (the path that the Sun appears to trace in the sky during the year). This is possible if, as seems likely, he made systematic use of the gnomon, since the obliquity of the ecliptic is the primary natural measurement shown by the gnomon.

This is an extract from Anaximander: And the Nature of Science by Carlo Rovelli (Penguin Books)

We’ll be chatting to Carlo Rovelli on “A Drink with the Idler”, Thursday 23 March at 6pm London time. Book your tickets here. Free to Idler magazine and Academy subscribers.

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