Anaximander

Anaximander (c. 610 to c. 546 BC) was an ancient Greek philosopher and geographer from Miletus, an Ionian city on the western coast of what is now Turkey. He belongs to the Milesian school founded by Thales, whom he succeeded as its leader. He is a key figure among the pre-Socratic thinkers, because he tried to explain the origin and structure of the world through natural causes and reasoned argument rather than through myth.

Very little is known about his life. According to Apollodorus of Athens, he was sixty-four years old around 547-546 BC and died shortly afterwards, which places his birth around 610 BC. He lived at a time when Polycrates ruled Samos as a tyrant. He is usually considered a pupil of Thales, although the exact nature of that relationship is debated, and a companion of Anaximenes, who carried the Milesian tradition forward. According to Aelian, the people of Miletus entrusted him with leading a colony at Apollonia, on the Black Sea coast, which suggests he enjoyed some public standing. Themistius describes him as the first Greek to publish a written work on nature, which would place his text among the earliest prose writings in Greek. That book, commonly called On Nature, has been lost. We have only fragments, preserved through Aristotle, Theophrastus and several doxographers. By Plato's day his ideas seem to have been largely forgotten.

His central idea is the apeiron, the indefinite or unlimited. It is not water, air or any of the familiar elements, but a boundless reality from which all things arise and to which they return. The apeiron is eternal and imperishable, and out of it the opposites separate: hot and cold, wet and dry. These opposites take turns in dominance within a cycle that restores balance. The one surviving fragment frames this in the language of justice: things pay one another a penalty for their injustice of existing separately, according to the order of time. It is best read as an image of the necessity that governs change rather than as a moral doctrine.

In cosmology he proposed that the Earth is a finite body, shaped like a cylinder or drum, held in balance at the centre of the universe, with sky both above and below it. He described the heavenly bodies as rings or wheels of fire and air at different distances, breaking with the older picture of a solid vault enclosing the world. He noticed that the water levels seemed to be falling and concluded that the Earth was drying out. In physics he explained rain, winds, thunder and earthquakes through natural causes, giving the gods no causal role. He is also credited with introducing the gnomon to Greece and with drawing a map of the known world. He further held that the first animals came from water and that humans descend from water-dwelling creatures, an intuition often compared with modern evolutionary theory, although our sources for it are indirect.

His influence is twofold. He is regarded as the first to adopt a naturalistic view of the world, and his work opened the way to physics, geography, meteorology and biology. His notion of the apeiron also lifted Greek philosophy to a new level of abstraction. The philosopher of science Karl Popper saw his ideas as a forerunner of Aristarchus, Copernicus, Kepler and Galileo. Because his work is lost, his thought can only be reconstructed from the quotations and reports of others, and many details remain a matter of scholarly debate.