The Greek natural philosopher and astronomer Anaximander (611 BC-ca. 546 BC) attempted to explain the origins of the universe through his theory of the apeiron.

Born in Miletus, Anaximander was the son of Praxiades. According to tradition, he was a pupil of the Greek philosopher Thales. Anaximander is said to have taken part in the founding of Apollonia on the Black Sea and to have traveled to Sparta. His book, On Nature, a title given by Alexandrian scholars to many works of its type, was still in use some 2 centuries after his death.

Anaximander was concerned with the origin of things. He found an explanation, having abandoned with Thales the old mythological cosmogonies, in his theory of the apeiron (the infinite)--that is, the universe is boundless and formless but is constituted of a single primary substance out of which all individual phenomena arise. This concept is similar in some respects to the "abyss" found in Eastern cosmogonies. Connected with the process of genesis and dissolution is dike, or justice, which works inexorably through the ages. Individual existences commit injustice against each other simply by coming into being and thereby lessening each other's viability, but atonement is made when dissolution comes to the transgressor in its turn.

The earth, in Anaximander's scheme, is shaped like a cylinder and floats at the center of the universe. There would therefore be no reason for it to fall in one direction or another. He believed that the earth was originally covered with water, it dried in part, and man sprang from aquatic forms which had moved onto the drier parts and adapted themselves to the new conditions. The stars, in his bold theory, were really parts of a great outer fire surrounding the compressed air that encircled the earth and they could be glimpsed through holes or vents in that atmosphere.

Anaximander was credited in antiquity with having introduced the gnomon (a sundial with a vertical needle) into Greece, with which he was able to determine the equinoxes. He is also reputed to have been the first Greek to draw a map of the inhabited earth and to teach a doctrine of organic evolution. Although it is difficult to assess his contribution properly because of the defective information about Greek philosophy before Plato, he appears as a boldly imaginative thinker who broke with the mythological explanations of the universe found in the Greek poetic and religious tradition in favor of explanations based on logical premises.

Further Reading

• Selected passages from the fragments of Anaximander, with English translation and commentary, are in G.S. Kirk and J.E. Raven, The Presocratic Philosophers: A Critical History with a Selection of Texts (1962). Among the specialized studies of Anaximander, Charles H. Kahn, Anaximander and the Origins of Greek Cosmology (1960), is noteworthy. There are excellent discussions of Anaximander in John Burnet, Early Greek Philosophy (1892; 4th ed. 1930), and Kathleen Freeman, The Pre-Socratic Philosophers (1946; 2d ed. 1959). Albin Lesky, A History of Greek Literature (1958; new ed. 1963; trans. 1966), is also useful.
• Gnagy, Allan S., Thalaes, Anaximandros, Anaximenaes, Athaena: Exantas, 1991.