Ancient Greek philosopher Anaxagoras was the one who introduced the concept of the universal mind (nous) as the motive cause of the cosmos. The pre-Socratic philosopher (c. 500-428 BC) was a brilliant scientist who understood the rainbow phenomenon and as an avid astronomer discovered the true cause of eclipses.
Anaxagoras was a materialist, believing that the natural world could be understood if one grasped the logical nature of substance, meaning ‘what is,’ and the mind. He was the first to claim that celestial bodies such as the sun, moon, and stars were not divine beings but fiery masses of red-hot metal.
His belief was that the universe was not the creation of divine beings but the result of a complex interaction of physical substances. This was considered impious by his contemporaries in Athens who eventually brought him to trial.
Anaxagoras Brings Scientific Philosophy to Athens
Born in Clazomenae of Anatolia (then occupied by the Persians) in c. 500 BC, Anaxagoras came from a wealthy family. It is said that he neglected affluence to devote his life to science.
He relocated to Athens in 480 BC. At the time, the Athenians were basking in the city’s Golden Age (c. 480-408 BC), also known as the Age of Pericles. Athens was the center of culture, a fertile ground for the philosopher from Ionia to practice his art in the spirit of scientific inquiry.
Anaxagoras is known for introducing philosophy based on scientific research to the Athenians, who were, nevertheless, not by any means ready to accept such a scientific approach to philosophy. He befriended the ruler of Athens, Pericles, who was also an inquiring mind. Pericles was the founder of democracy.
However, the philosopher’s friendship with Pericles had its drawbacks as the statesman’s enemies turned against the philosopher.
The Ancient Greek Philosopher’s One Book
There is little known about the life of Anaxagoras. He wrote only a single book in prose titled On Nature, setting out his theories concerning astronomical, meteorological, and biological phenomena.
Unfortunately, like the works of the other pre-Socratics, only fragments survive, mainly as quotations in the writings of later philosophers such as Simplicius, Plutarch, and Sextus Empiricus.
The basic features, however, are clear. While his predecessors had attempted to explain the physical universe by an assumption of a fundamental element or a number of elements, Anaxagoras posited an infinite number. Unlike his predecessors, who had chosen such elements as heat or water as the basic substances, the Greek philosopher included those found in living bodies—flesh, bone, bark, and leaf.
He asked how flesh could come from something that is itself not flesh. He also accounted for biological changes in which substances appear under new manifestations. As men eat and drink, for instance, flesh, bone, and hair grow, he said.
In order to explain the great amount and diversity of change, he posited that “there is a portion of every thing, i.e., of every elemental stuff, in every thing.”
Cosmogony, Seeds, and Nous
For Anaxagoras, in the beginning of the cosmos, there was not one but two principles all infinite and everlasting in nature: Mind (Nous) and the Primeval Mixture (Migma). In the beginning ‘everything was in everything.’ The revolutionary formation of the cosmos started when the infinite ‘seeds’ (spermata) within the primeval mixture separated by the motive power of Mind.
Mind initiated the rotation of the ‘seeds,’ resulting in the predominantly heavy parts coming to the center of the vortex and the subtler parts in outer areas. The ingredients of the primeval mixture were an infinite number of ‘seeds’ containing opposites, such as the binary opposites of wet and dry, hot and cold, bright and dark.
The ‘seeds’ are not generated nor destroyed. They are combined in various ways but are ultimately indivisible, imperishable elements that are infinite in number and vary in shape, color, and taste. Each material contains a piece of every other substance.
Mind (nous) is the motive force that initiated the primeval matter. Mind is completely separate from matter and is the only exception to the universal criterion ‘everything in everything.’ Matter under the control of Mind expands continually and indefinitely outwards from the single place of origin—a mere dot—which contained everything in the whole universe, the Greek philosopher said.
Nous is described as unlimited, self-controlling, unmixed, and of a singular nature by itself, but it is also the finest and purest, possessing complete knowledge, supreme power, and the ability to control everything alive, according to Anaxagoras.
Anaxagoras the Astronomer
Through persistent observation, Anaxagoras came to believe that the moon was a rock, not totally unlike the Earth, and he even described mountains on the lunar surface. The sun, he thought, was a burning rock. In Fragment 18, Anaxagoras wrote, “It is the sun that puts brightness into the moon.”
He was not the first to realize that moonlight is reflected light from the sun, but he was able to explain additional phenomena, such as eclipses and lunar phases. The moon’s phases, the Greek philosopher realized, were the result of different portions of the celestial object being illuminated by the sun from Earth’s perspective.
The philosopher also realized that the occasional darkening of the moon must result from the moon, sun, and Earth lining up in such a way that the moon passes into the Earth’s shadow—a lunar eclipse.
When the moon passes directly before the sun, the skies darken during the day, Anaxagoras also explained. He wrestled with the origins and formation of the moon, a mystery that continues to challenge scientists to this day. The philosopher posited that the moon was a large rock that the early Earth had flung into space.
By describing the moon as a rock of terrestrial origin and the sun as a burning rock, Anaxagoras moved beyond earlier thinkers and those who realized the moon was a kind of reflector.
Brought to Trial for Impiety
Anaxagoras’ radical thinking denied any divinity to the cosmos and maintained that the celestial bodies such as the sun, moon, and stars were not divine beings but fiery masses of red-hot metal.
This theory was probably based on a meteorite that fell to earth at Aegospotami in 467 BC. Anaxagoras also put forward the theory that the rainbow is a reflection of the sun in the clouds and maintained that the moon has dwelling places, hills, and ravines. Owing to his materialism, Anaxagoras was brought to trial for impiety and sentenced to death.
He is usually considered to be the first philosopher prior to Socrates to be charged with impiety, but, in contrast to Socrates, he was merely exiled from Athens. This was probably because Pericles intervened, and his death sentence was converted to exile. The great philosopher spent the rest of his life in the Ionian town of Lampsacus.
It is said that, in appreciation of his work, the citizens of Lampsacus erected an altar to Mind and Truth in his memory. They also observed the anniversary of his death for many years after.
Over his grave the following inscription was placed:
Here Anaxagoras, who in his quest of truth scaled heaven itself, is laid to rest.