Anaxagoras

Anaxagoras (c. 510 – c. 428 BC) was a Pre-Socratic Greek philosopher born in Clazomenae who is credited with bringing philosophy and scientific inquiry to Athens, best known for his cosmological theory that introduced Nous (Mind) as the supreme ordering principle of the universe and his doctrine that "everything is in everything."

Biography

Born into a wealthy and prominent family in Clazomenae, a city in Ionia (modern-day Turkey), Anaxagoras renounced his inheritance and political prospects to dedicate his life to the pursuit of knowledge. Around 460 BC, he relocated to Athens, where he resided for approximately thirty years. During this period, Athens was entering its Golden Age, and Anaxagoras became a central figure in its intellectual circles. He formed a close friendship with the statesman Pericles and was associated with the playwright Euripides, who is said to have been influenced by the philosopher's ideas.

Anaxagoras's scientific teachings eventually brought him into conflict with Athenian religious orthodoxy. His assertion that the sun was not a god but a red-hot mass of metal, and that the moon was an earthy body reflecting the sun's light, led to charges of impiety (asebeia). Historical accounts vary regarding his exact fate; some suggest he was imprisoned and subsequently released due to Pericles' intervention, while others claim he was exiled or fled the city to avoid prosecution. He spent his final years in Lampsacus, a city in the Troad. Upon his death around 428 BC, the citizens of Lampsacus honored him by erecting an altar dedicated to Mind and Truth, and they established an annual holiday for schoolchildren on the anniversary of his passing.

Philosophy

Theory of Matter

Anaxagoras formulated a unique theory of matter to address the Eleatic philosopher Parmenides' argument that nothing can come from nothing, meaning true creation and destruction are impossible. Anaxagoras agreed, positing that "nothing comes into being or perishes, but is mixed together and separated from things that are."

He argued that matter is infinitely divisible. Unlike the later atomists who believed in indivisible particles, Anaxagoras maintained that every substance contains "seeds" (spermata) of every other substance. According to his doctrine, a piece of gold appears to be pure gold because it contains a preponderance of gold seeds, but it also contains microscopic portions of bone, flesh, water, and all other existing qualities. This concept is summarized by his famous maxim, "everything is in everything." The perceived nature of an object is simply determined by which type of seed predominates in its mixture.

Nous (Mind)

To explain how the original, static, and chaotic mixture of all things was set into motion and organized into the structured cosmos, Anaxagoras introduced the concept of Nous (Mind or Intellect). He described Nous as infinite, self-ruled, and completely unmixed with any other substance. It is the finest and purest of all things, possessing all knowledge and the greatest power.

Nous initiated a cosmic rotation (a vortex) that caused the separation of the primordial mixture. This mechanical rotation led to the differentiation of hot and cold, light and dark, and the eventual formation of distinct objects, celestial bodies, and living organisms. While Nous is the initial mechanical cause of the universe's motion, Anaxagoras did not use it as a teleological or moral force that designs the universe for a specific purpose. This purely mechanical application of Nous later drew criticism from Socrates and Plato, who sought a more purposeful, divine intelligence behind natural phenomena.

Scientific Contributions

Astronomy

Anaxagoras made significant strides in early astronomy, moving away from mythological explanations toward empirical observation. He correctly deduced that the moon does not emit its own light but reflects the light of the sun. Building on this, he provided the first accurate scientific explanation for solar and lunar eclipses, attributing solar eclipses to the interposition of the moon between the earth and the sun, and lunar eclipses to the earth's shadow falling on the moon. He also theorized that the stars were fiery stones, but that their immense distance prevented their heat from reaching the earth.

Earth and Meteorology

In his cosmological model, Anaxagoras believed the earth was flat and rested on a cushion of "strong air." He explained earthquakes as the result of air occasionally slipping beneath the earth's surface. Anaxagoras also investigated meteorological phenomena, attributing thunder to the collision of clouds, lightning to the friction of clouds producing fire, and wind to the movement of air from areas of high pressure to low pressure.

Notably, following the fall of a large meteorite at Aegospotami in 467 BC, Anaxagoras concluded that celestial bodies were not divine beings but massive, incandescent stones that had been torn from the earth by the force of the cosmic rotation. This naturalistic view of the heavens was highly controversial in his time but laid the groundwork for future astronomical science.

Legacy and Influence

Anaxagoras played a pivotal role in the intellectual history of ancient Greece by shifting the center of philosophical activity from Ionia and Magna Graecia to Athens, setting the stage for the subsequent achievements of Socrates, Plato, and Aristotle. His writings, composed in prose, survived in fragments quoted by later authors such as Simplicius.

His concept of Nous profoundly influenced subsequent philosophical thought. Although Socrates was disappointed by Anaxagoras's failure to use Nous as a teleological explanation for nature, the concept prompted Socrates to explore purposeful design, which in turn became a cornerstone of Platonic and Aristotelian philosophy. Furthermore, his theory of infinitely divisible matter contributed to the ongoing ancient debates regarding the composition of the physical world, serving as a crucial counterpoint to the atomism of Leucippus and Democritus.