Anaximander of Miletus was a Greek pre-Socratic philosopher, astronomer, mathematician, and geographer. He was a member of the Milesian School and master of Anaximenes of Miletus.

His theory of arche is considered one of the first attempts to explain the origin of the universe without resorting to myths or gods.


Anaximander, a disciple of Thales, was born in the city of Miletus, in Ionia, around 611 BC, and died in 547 BC.

He was known for his interest in astronomy, and is credited with creating a globe and a world map. In addition, he is said to have invented the gnomon[1], a sundial that he used to observe and determine the solstices, the time, the seasons, and the equinoxes.

A gnomon
Gnomon: an ancient astronomical instrument used to determine time through the shadow it casts.


Anaximander wrote a work entitled On Nature, of which few fragments remain.[2]

Anaximander’s philosophical ideas are largely known through quotations from other philosophers, such as Aristotle, Simplicius, and Aetius. This limitation makes it challenging to reconstruct his thought in an accurate and systematic way.

Anaximander by Raphael Sanzio
Anaximander, The School of Athens, by Raphael Sanzio, 1510-1511.

Anaximander’s Apeiron

For Anaximander, the arche (the principle of things), is the apeiron (ἄπειρον), which in Greek means ‘boundless’, ‘infinite’, ‘indefinite’, etc.

The apeiron, according to Anaximander, is eternal and never had a beginning. This fundamental principle is present in all things, sustaining and governing the universe, and through it, all things are generated. The apeiron is an “anonymous” principle, not perceptible and of undefined nature.

Through this boundless principle all things come into existence, and all things return to it. Anaximander says:

The apeiron (boundless) is eternal;

The boundless is immortal and indissoluble.

Anaximander did not explain the origin of things by the change of primordial elements (as some pre-Socratic philosophers would later argue), but rather by the separation of opposites as a result of eternal motion.

The origin of things and opposites

According to Anaximander, opposite elements are in constant struggle.

The opposites (e.g. hot and cold, dry and wet, etc.) are in conflict and can be united or separated. Anaximander says about this:

All things dissipate where they had their origin, according to necessity; for they pay each other punishment and expiation for injustice, according to the ordinance of time.

In nature, one opposite tends to destroy the other. For example, when fire and water meet, there is a struggle until one prevails over the other. It is through the separation of opposites that all things are created.

Cosmology and cosmogony

According to Anaximander, the Earth has a cylindrical shape, and remains fixed, at absolute rest.

Cylindrical earth
Anaximander’s Cylindrical Earth

The light of the moon is generated by the luminosity of the sun, and the sun, being as large as the earth, is pure fire. Because of the birth of the cosmos, the creative force of the principle separated from heat and cold, forming a sphere of this fire around the air.

Anaximander describes the order of the world by the separation of the opposites, resulting from an eternal movement in the apeiron. As related by Hippolytus, Anaximander is said to have affirmed that “motion is eternal and it is from it that the heavens arise.

Moreover, he believed in infinite worlds, distant from each other.

The concept of God

Anaximander’s conception of God is in line with his conception of ápeiron, in which God is the Infinite and boundless Principle, while other gods are considered worlds.

God, as an indeterminate principle, is neither born nor perishes, but gods (worlds) are born and die cyclically.

Origins of animal life and human beings

Anaximander explains the origin of animal life by again resorting to opposites and evolutionary processes.

According to him, animals were born out of the wet, covered by a spiny bark. As time passed, these animals ascended to the dry, broke their barks and acquired new forms of life.

The human being, on the other hand, would have emerged from inside the fish, and after being nourished and acquiring the ability to protect themselves, they were expelled and thrown to the earth.

Synoptic table

Anaximander of Miletus
Bornc. 611 BC. – Miletus
Diedc. 547 BC.
WorksOn Nature
SchoolMilesian School
Key IdeasApeiron as arche
Evolutionary conception of life
InfluencesThales of Miletus


  1. The historian Herodotus claimed that it was from the Babylonians that the Greeks learned to use the Gnomon for astronomical purposes. Anaximander would then only have imported this instrument to Greece.
  2. The name of the work, On Nature, was a generic name often given to the writings of the pre-Socratics, since the philosophers of this period were interested in explaining the principle and constitution of nature (physis).


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