ASTRONOMER, PHYSICIST

Life
One of the major philosophers of the ancient world, Anaxagoras was born in the Ionian city of Clazomenae. From a very early age he devoted himself to study, and showed outstanding mental abilities. Attracted by the glory of Athenian democracy he travelled to Athens, where he soon became a close friend of Pericles, the great statesman and founder of democracy in Athens, and many other prominent figures of the age, including Socrates and Euripides. In 430 BC, however, he was accused of impiety, and was tried and sentenced to imprisonment under the law prohibiting the teaching of atheistic doctrines and theories referring to celestial phenomena. Compelled to leave Athens (apparently having managed to escape from his prison), Anaxagoras retired to Lampsacus, where he lived until 327 BC. There he founded a school of philosophy which became famous. His philosophy was based on the natural philosophy of the Ionian School; he taught that matter was infinite and circulated in successive transformations. In his view, the driving force behind all movement and change was Mind (nous); and since he was the first to introduce this concept into accounts of the cosmos, his contemporaries often referred to him by this name.


Work
His writings on astronomy are particularly interesting. He is said to have predicted the fall of a meteorite at Aegospotami in 467/466 BC: for many years this stone - which was the size of a mill-stone - was shown off to visitors by the people of Abydos on the Hellespont. On another occasion he went to Olympia all dressed in leather, to protect himself from the rainstorm which he had predicted, and which did indeed occur shortly afterwards.

His theories are resumed in his treatise "On Nature", where he says that there is no "coming-into-being" or "passing-away", but rather aggregations and segregations of matter. The universe was in the beginning a chaos of innumerable "seeds", which "Mind" ordered into shape in a series of "successions". "On Nature" also contains his commentaries on the fall of the meteorite at Aegospotami.

Many fragments of his work survive. The rules enunciated in his treatise on descriptive geometry, entitled "Perspective", found wide application in the theatre.

In his "Cosmogony" he argued that the universe was created by a whirlwind created by nous (God): up to a point his work underlies the theories of Kant and Laplace. He also stated that the moon is not self-luminous, but takes its light from the sun; he correctly interpreted lunar and solar eclipses; and he correctly ascribed the flooding of the Nile to the melting of the snows in Ethiopia. Finally, he wrote at length on the squaring of the circle.