Information about Anaxagoras and his works is incomplete and contradictory. Only fragments of his book on natural history survive; most of these are quoted in the seventh century c.e. writings of Simplicius, who may have quoted them from another source. Others assert that Anaxagoras’ book was lost as early as the third century b.c.e. In addition to these fragmentary texts, Aristotle and Plato describe Anaxagoras’ concepts and philosophy. From these sources, several contrasting versions of Anaxagoras’ works have been constructed. Despite inconsistencies, a general understanding of Anaxagoras’ contributions to the philosophy of science does exist.
Anaxagoras’ treatise on natural philosophy became a standard text in ancient Athens. In contrast to earlier Greek thinkers, he postulated an infinite number of fundamental elements in the universe, rather than one or a few elements. He also asserted that nous, or mind, created the cosmos. According to Anaxagoras, nous first formed all of the elements by a process of mixing and revolving. Thus all of “the dark” came together to form the night, all “the fluid” formed the ocean, and all other elements formed similarly. During a second stage flesh and other elements were brought together by nous to create living things. Because ethical concerns are not addressed in Anaxagoras’ cosmology, it was later criticized by Aristotle and Plato. However, this omission and Anaxagoras’ scientific inquiries—such as his discovery of the true cause of eclipses—make him the earliest known natural philosopher, or true scientist.
Around 480 b.c.e. Anaxagoras moved to Athens, where he probably remained for thirty years. While there he attracted a “school” and was accepted in the highest circles. Pericles was one of his students and openly acknowledged his indebtedness to Anaxagoras. Aristotle based part of his work on that of Anaxagoras, some of whose teachings were inserted into drama, either seriously or as subjects for lampoon. Around 433-430 b.c.e., Anaxagoras was prosecuted by Cleon for impiety and atheism. Anaxagoras’ statement that the sun was an incandescent stone somewhat larger than the Peloponnese Peninsula was given as the reason for his prosecution; however, it is thought that the prosecution was actually an attack upon Pericles. Pericles was able to save Anaxagoras’ life, but could not prevent his exile. Thereafter Anaxagoras resided at Lampsacus where he reestablished his school and continued his work until his death.
Biography (World Philosophers and Their Works)
Article abstract: By devising a philosophical system to explain the origins and nature of the physical universe that overcame the paradoxes and inconsistencies of earlier systems, Anaxagoras provided an indispensable bridge between the pre-Socratic philosophers of the archaic period of Greek history and the full flowering of philosophy during the Golden Age of Greece.
Virtually nothing is known of Anaxagoras’s parents, his childhood, his adolescence, or his education. Born into a wealthy family in an Ionian Greek city around 500 b.c.e., he almost certainly was exposed to the attempts by Ionian philosophers, especially Parmenides, to explain the physical universe by postulating that everything is made from a single primordial substance. Anaxagoras apparently realized even before he was twenty years old that such an assumption could not explain the phenomena of movement and change, and he began to devise a more satisfactory system.
He grew to adulthood during the turbulent years of the wars of the Greek city-states against the Persian Empire. His own city, Clazomenae, forced to acknowledge the suzerainty of Darius the Great in 514 b.c.e., joined the Athenian-aided Ionian revolt against Persia in 498. That revolt was ultimately suppressed in 493. Anaxagoras’s childhood was spent during a time when the echoes of the great victory of Athens over Darius at Marathon in 490 were reverberating throughout the Hellenic world.
According to tradition, Anaxagoras became a resident of Athens in 480 b.c.e. That a young scholar should be attracted to the intellectual and artistic center of Greek civilization is not surprising, but it is doubtful that this change of residence took place in 480. Xerxes I chose that year to attempt to realize Darius’s dream of conquering the Greek polis, but his plans were frustrated and his great host scattered at the battles of Salamis and Plataea. The next year, the Ionian cities of Asia Minor again rose in rebellion against Persia and in 477 joined with Athens in the Delian League. The League succeeded in expelling the Persians from the Greek states of Asia Minor. It seems more likely that the young Anaxagoras came to Athens after the alliance between the Ionian cities and the Athenians.
While in Athens, Anaxagoras became friends with the young Pericles and apparently influenced him considerably. Several classical scholars have concluded that Anaxagoras’s later trial was engineered by Pericles’ political rivals in order to deprive Pericles of a trusted friend. Convicted of impiety after admitting that he thought the Sun was a huge mass of “hot rock,” Anaxagoras went into exile at Lampsacus, where many young Greeks came to study with him before his death, probably in 428 b.c.e..
Sometime in or shortly after 467 b.c.e., Anaxagoras published his only written work, apparently entitled “On Nature.” Of this work, only seventeen fragments totaling around twelve hundred words have survived, all recorded as quotations in the works of later generations of philosophers. That so few words could have inspired so much study is ample testimony to Anaxagoras’s importance in the evolution of Greek philosophy and natural science.
Anaxagoras’s book was an ambitious attempt to explain the origins and nature of the universe without recourse (or so it seemed to many of his contemporaries) to any supernatural agents. Other Ionian philosophers, notably Parmenides, had preceded Anaxagoras in this endeavor, but their systems were logically unable to explain the multiplicity of “things” in the universe or to explain physical and biological change in those things because they had postulated that all things are made from the same basic “stuff.” Anaxagoras overcame the logical inconsistencies of this argument by postulating an infinite variety of substances that make up the whole of the universe. Anaxagoras argued that there is something of everything in everything. By this he meant that, for example, water contains a part of every other thing in the universe, from blood to rock to air. The reason that it is perceived to be water is that most of its parts are water. A hair also contains parts of every other thing, but most of its parts are hair.
In the beginning, according to the first fragment of Anaxagoras’s book, infinitely small parts of everything in equal proportion were together in a sort of primal soup. In fragment 3, he proposes a primitive version of the law of the conservation of energy, saying that anything, no matter how small, can be divided infinitely, because it is not possible for something to become...
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