Anaxagoras c. 500 BC – 428 BC) Pre-Socratic Greek philosopher. Brought the spirit of scientific inquiry from Ionia to Athens. He attempted to explain the workings of the cosmos; the goal was scientific understanding, as far as that is possible for human beings. His account included explanation of eclipses, meteors, rainbows, thunder and lightning. and the sun as a fiery mass larger than the Peloponnese. The moon, he said, has its light from the sun. He introduced the concept of Mind (Nous), as a universal ordering force. "Nous has control over all things that have soul, both the larger and the smaller, the purest and finest of all things; Nous is the most powerful thing in the cosmos, controlling the rotation and all things with souls. Mind is infinite and self-powerful and mixed with nothing, but it exists alone itself by itself. Nothing is absolutely separated nor distinct, one thing from another, except mind. Anaxagoras accepted from Parmenides the rejection of any notion of things coming into existence from nothing or ceasing to exist and become nothing. There is no void from which new being could emerge or into which existing being could disappear. Matter was formed from an infinite multitude of imperishable primary elements. Apparent change is really the result of mixture and separation, not of an impossible creation or destruction of being. Anaxagoras is included in the ancient lists of those who wrote only one book; in the Apology, Socrates reported that it could be bought for a drachma. According to Simplicius (a neo-Platonist commentator on Aristotle), Anaxagoras began his book by describing an original state of complete (but not entirely uniform) mixture of all the ingredients of the cosmos; that mixture is then set in motion by the action of Mind. A fragment in Simplicius seems to suggest that Anaxagoras envisaged the existence of other worlds like our own. From Aristotle: "Anaxagoras says that man is the most intelligent of animals because he has hands. Anaxagoras was satisfied with saying that the void does not exist, nevertheless he says beings move, though there is no void. According to Anaxagoras, all things being made up of like parts; they arise and perish only by composition and separation. There is no other arising and perishing, but they abide eternal." Pericles was a friend and Euripides a pupil; Euripides said that "mind is god in each of us." Anaxagoras’ work was known to Sophocles, perhaps to Aeschylus and certainly to Aristophanes (who in his play The Clouds mocked both Socrates and Anaxagoras).

As with all the Presocratics, Anaxagoras' work survives only in fragments quoted by later philosophers; there are commentaries on his views in many ancient sources. The fullest account was provided by Dioegenes Laertius - from which the immediately following extracts are drawn:

"He [Anaxagoras] said that the sun was a mass of redhot metal, in size greater than the Peloponnesus"

and that "the whole universe had been made from putting together small physical particles"

"and Mind [nous] was the originating principle of movement"

wherefore they came to call him by the name Nous himself.

Anecdotes of Anaxagoras:

When he abandoned politics to concentrate on studying the physical world and someone asked him "Have you no concern at all for your country?", he replied "My greatest concern is for my own fatherland" and he pointed to the vault of the sky.

When he was asked what was his mission in life, he said "To contemplate the sun and the moon and the heavens"

To someone who was grieved by the thought of dying in a foreign land, he said "Wherever we start from, the descent to death (Hades) is the same"

When he was told that he had been sentenced to death, he said "Long ago nature condemned both my judges and myself to death" When he died, the people of Lampsacus gave him a noble funeral and over his grave placed this inscription:

"Here lies Anaxagoras who in the quest for truth
reached out to the skies and all the universe."

They erected an altar to Mind and Truth in his memory, and observed the anniversary of his death for many years.