Greek philosopher of Elea, founder of the Eleatic school which believed in unity and continuity of being and unreality of change or motion.

Parmenides was a Greek philosopher who lived around 500 BC. Parmenides was born in Ela, a Greek colony in southern Italy. He was one of the first Greek philosophers to express his thought in poetry.

He played an important part in developing pre-Socratic philosophy. Before Parmenides, philosophers generally tried to explain the origin and nature of the universe in terms of one material substance, such as air. Parmenides used logical arguments to support his belief that what exists is one, eternal, indivisible, motionless, finite, and spherical. Therefore, it cannot become something else and other things cannot be explained by reference to its changing states.

Change and plurality (reality consisting of many substances) are illusions.

His poem On Nature, is divided into two parts. What is probably most of the first part has survived.

The teachings of Parmenides, which became influential during the 400's BC, raised a problem for other Pre-Socratics. Until them, philosophers had accepted the existence of change, motion and plurality (reality consisting of many substances). Parmenides held that change, motion and plurality were unreal because they require the existence of what is not. Parmenides rejected the idea of what is not as inconceivable . He said the universe is uniform, immovable and unchanging, with no generation of destruction.

Parmenides had great influence but few followers. His opponents could not disprove his reasoning, and so they tried to reconcile his conclusions with common sense. Empedocles agreed that there could be no generation destruction. He explained the apparent existence of such things in terms of four eternal elements - earth, air, fire and water - mixed by the force of love and separated by strife. Anaxagoras believed that an infinite number of elements had been separated out of an original mixture through the rotation initiated by a force he called mind. Each thing contains all the elements but in different proportions. Anaxagoras thought matter was infinitely divisible.

In the late 400's BC, Leucippus and Democritus responded to Parmenides with the theory called atomism, they taught that the universe consists of tiny, solid, indivisible bodies called atoms, which move about in space and cluster together to form the larger objects of common experience.

• Great Encyclopaedia Dictionary, Volume Two, 1965, Readers Digest

• New Encyclopedia, Volume 8, 1971, Funk & Wagnalls

• New Encyclopedia, Volume 18, 1971, Funk & Wagnalls

• Early Greek Philosophy, 4th Edition, 1964, Milton C. Nahm

• The World Book Encyclopedia, Volume 15, World Book Inc, 1985