Anaxagoras of Clazomenae Biography

World of Mathematics on Anaxagoras of Clazomenae

Anaxagoras of Clazomenaewas a Greek philosopher who made contributions in astronomy and physics. He was the first philosopher to live in Athens and the first to propose several important theories about the cosmos. Among these are theories about the Earth and moon, including the reason for an eclipse and accurate descriptions of the lunar surface. In mathematics, Anaxagoras was the first to attempt squaring the circle.

Not much is known about Anaxagoras life, though records of his theories are preserved. The Greek philosopher was born on the Ionian coast in the town of Clazomenae in Asia Minor (in what is now Turkey). His parents were wealthy but Anaxagoras chose to forsake his life of leisure to study philosophy. In 462 B.C., he moved to Athens, which was rapidly becoming an intellectual center. There he attracted the attention of the politician Periclesas well as the playwright Euripedes. Pericles welcomed Anaxagoras into his circle of friends.

Anaxagoras was the first to propose a molecular theory of matter. He believed that matterwas infinitely divisible. The universe, he said, began as a great whirling jumble of matter, which was controlled by the Mind. The Mind, however, was not a god, or a spiritual or mental essence. "It was the most delicate and purest of all things," Anaxagoras wrote. In Anaxagoras' theory of "nous" the Mind caused the dark and the light to form, creating air, water, and earth. In another stage, animal and plant seeds (which were part of the original mixture) came together to form flesh and vegetation. The growth of all living things occurred because they had portions of the Mind within them, which could attract nourishment.

Anaxagoras believed that objects of the natural world were elemental. That is, they could not have been derived from elements simpler than themselves, from things that were not made of the same material. Every single piece of matter came from something like itself. "How could hair come to be from what is not hair and flesh from what is not flesh," he asks in his writings. He believed that every element in the world--hair, skin, bone, and an infinite number of other things--preexisted in our food

The Greek philosopher was also a great astronomer. He was the first to propose the reason for an eclipse and the first to theorize that the moon shone by reflected light. He also described the moon's surface accurately as a series of flat areas and depressions. The moon was not a sphere, Anaxagoras said. This was a contention that was confirmed 2,000 years later when Galileo trained his telescope on the moon. Direct proof of this theory also came through the American astronauts' first trip to the moon.

Anaxagoras, however, created real problems for himself and his friends when he proposed that the sun was a red hot stone. All the planets and stars were, in fact, made of stone, he said. His belief may have been suggested by the fall of a huge meteorite near his home when he was young.

Anaxagoras' belief about the sun, however, made him a prime target for his and Pericles' enemies. They resented the attempts of Pericles, philosophers like Anaxagoras and artists like Pheidias to bring a higher culture to Athens. As Pericles grew aged, his enemies began to attack his friends. They accused Pheidias of stealing some of the gold used on his artistic statues. They campaigned for a law that permitted prosecution of those who did not believe in religion and taught theories about celestial bodies. Under this law, they brought Anaxagoras to trial.

It's not certain what was the result of the trial (records are not preserved), but we do know that while he was in jail, Anaxagoras made the first attempt to square the circle. In other words, he used a compass and a ruler to try to construct a square with the same area as a certain circle. This was the first time that such an effort had been made and preserved on record.

Pericles was able to get Anaxagoras released from prison. But Anaxagoras was forced to return to Ionia. There he started a school and was celebrated as a hero. He died in 428 B.C. and the anniversary of his death was celebrated for a century afterward in Ionia.