European history began with the emergence of Athens as the classical cosmopolis of the northern Mediterranean. Athena won a dispute with Poseidon for protective sovereignty over Attica by giving the area the sacred and nourishing olive tree, and her sacred bird, the owl, became the city's symbol. Doubly blest, Athens became the focus of the converging forces that would in a brief time initiate a culture of such creativity and splendour that subsequent generations in Europe would look to her as the source of science, ethics and knowledge of the soul. Athens first drew ideas to herself, and later attracted thinkers, until she housed the schools and traditions that provided the foundation of European thought. Perhaps even before the time of Homer, an incipient anthropomorphic decadence began to undermine the spiritual appeal of Mycenaean and Minoan mythology. The gods as personifications of intelligent forces in Man and Nature were degraded into beings that reflected only the most superficial human traits. As the Mysteries withdrew increasingly from the desecrating gaze of the public eye, though not from public knowledge, thinkers sought for new ways to vivify the deeper meanings of human existence. Early philosophers emphasized either an understanding of nature shorn of its anthropocentric excesses or the ethical dimension in the structure of the cosmos. Pythagoras and Plato brought this latter concern to sublime fruition, and Anaxagoras laid the foundation for experimental method and theoretical science.
Anaxagoras was born in the port city of Clazomenae in Ionia around 500 B.C., though almost nothing is known about his life or the order of happenings. His father, Hegesibulus, was extremely wealthy, and Anaxagoras apparently devoted the early years of his life to leisurely study. Though a Greek city, Clazomenae had fallen to the Persians, and it is likely that the thoughtful Anaxagoras would have learnt the rudiments of the religion taught by Zarathushtra, whom the Greeks called Zoroaster. Ahura Mazda, the Lord of Light, cannot be described in crude human terms, though Vohu Manah, Good Mind, the first aspect of manifest deity, is seen as that which orders and moves all things. Rather than a human form, Ahura Mazda and its seven aspects are best represented by an eternal fire and the seven-branched candelabrum. From the beginning of his active life, Anaxagoras made fire a central theme in his thought. When he was about twenty years of age, he journeyed to Athens, where his wealth (and perhaps his father's connections) gained him immediate entrance into the highest circles where he became good friends with Themistocles and Pericles. Though Pericles was probably never a student of Anaxagoras in a formal sense, he often acknowledged his debt to Anaxagoras for many of his ideas and policies, and eventually their relationship became famous.
Anaxagoras taught in Athens throughout his adult life. Sometime during that period he became the focus of opponents of Periclean political reform. Satyrus wrote that Thucydides, a long-standing enemy of Pericles, found it impossible to confront his opponent successfully, and so attacked him indirectly by bringing charges of asebeia (impiety) against Anaxagoras. Since the Athenians officially held the sun to be a deity, the view held by Anaxagoras that the sun is like a molten stone was construed by some as impiety. But Thucydides also charged him with treason in the Persian wars. Anaxagoras fled Athens and only later returned with full pardon after Pericles had more firmly secured his own position. Sotion, however, wrote that Anaxagoras had been charged with impiety late in life for his teachings about the sun and that he was forced into exile. Whatever the literal truth, Anaxagoras lived in tumultuous as well as glorious times, and it would not have been impossible for him to be exiled twice. Though vulnerable because of his acquaintances, Anaxagoras neither took part in the political life of the city nor paid any attention to the opinion of others. Much to the dismay of friends and relatives, he allowed his extensive inheritance to waste away, either permitting his farmland to return to pasture or giving it to relatives. His concern lay wholly in the contemplation of heaven and earth.
Anaxagoras was not the first Greek to observe nature studiously, though he was an exceptionally careful scrutinizer of phenomena. For example, painstaking observation led him to the discovery that the image reflected in the dark pupil of the eye constitutes the exact field of vision. Whilst others were teaching that the whole eye saw, he correctly identified the pupil as the active window of perception. Observation alone, however, was insufficient to discover the causes of things. Anaxagoras developed the method of experimentation as a means of confirming explanations of natural processes. His observations of wind blowing through trees convinced him that gases exert pressure, but to convince a sceptical Athenian audience, he filled a bladder with air and sealed it shut, and then invited challengers to crush the bag. Since air was trapped inside, he surmised that the air exerted pressure which manifested as resistance to anyone attempting to flatten the bag. Besides observation and experimentation, Anaxagoras recognized the need for a unity of explanation, a coherence of theory, to account for nature. Though he did not emphasize the mathematical nature of the world as did Pythagoras, Anaxagoras drew together the other elements of scientific endeavour, laying down the broad foundations of scientific method used even to this day.
His concern with explaining the occurrence of natural phenomena in terms of invariable laws and not special circumstances – such as the whimsy of capricious deities – along with his reticent form of life resulted in the status of prophet being attributed to him. On the basis of his theory of the stars and planets, he argued that it was possible for rocky material to fall from them to earth. When a meteorite fell to earth at Aegospotami, perhaps during his lifetime, the legend arose that he had predicted it in detail. His grasp of the nature of eclipses enabled him to inform Pericles of the time of a total solar obscuration, and the statesman used that advance knowledge to reassure the Athenians when it occurred. Ammianus Marcellinus wrote that Anaxagoras had gained such knowledge in Egypt. Plutarch asserted that he had mastered geometry and had successfully squared the circle. Satyrus reported that Euripides greatly admired him and might even have been his student. Theodoretus supported the less likely possibility that Socrates as a youth studied with Anaxagoras.
Anaxagoras followed the tradition of his day and taught students who came to hear him discourse, but he did not establish a permanent school. Nevertheless, like Parmenides, he wrote one book outlining his methodology and explanations of nature. Since Parmenides had taught that change was logically impossible, the work of Anaxagoras, taking change as fundamental to nature, became the standard text for nascent Athenian science. Socrates is made to refer to this work in Plato's Apology and to criticize its approaches in the Phaedo, where he does not say Anaxagoras is wrong but rather that his explanations of behaviour are inadequate when applied to human action. The strong motivation to understand nature so profoundly moved Anaxagoras that he renounced concern for his own welfare, exemplified in his abandonment of his large inheritance, withdrew from the exciting public affairs of the day, and remained aloof from personal involvements of every kind. His detachment from worldly involvements became legendary when he responded to a report of his son's death by saying that he knew that his son was mortal from the moment of his birth. When asked why one should be pleased to have been born rather than not, he answered, "In order to contemplate the heavens and the structure of the world-order as a whole." This constitutes the truly happy life, Anaxagoras said, though most people would not think so.
Anaxagoras lived in Athens for about thirty years, a time spanning the golden age of classical Greek culture. He represented the rational approach to understanding events and things, advocating a calm and detached perception supported by an alert mind, freed from the obscuring clouds of unrestrained emotion and self-seeking bias. Near the end of his life he left Athens, perhaps because he was again charged with impiety, and retired around 433 B.C. to the Hellespontine city of Lampsacus. There he was welcomed, surrounded by students and honoured by the citizens. When he died in about 428 B.C., he was given a public funeral, and the citizenry inscribed a tribute on his tomb:
Shortly before his death his followers asked him what he would consider an appropriate way to honour his memory. He replied that students should be given the month in which he died as a vacation each year. Anaxagoras was so highly respected in Lampsacus that his death was observed as he wished for well over a century.
The scientific philosophy developed by Anaxagoras rested upon two fundamental convictions: that nature and all its operations are rational, i.e., accessible to understanding through reason, and every account of nature must be consistent with and explain observed phenomena. Affirming that "visible things are a sight of the unseen", he did not think that universal order is limited to the empirical realm, but only that any explanation of Nature must take visible nature into account. His physics began with the theoretical assumption that matter is eternal, for without it one has to explain wholly unobserved processes of matter coming into existence from immateriality. Anaxagoras also recognized that the fundamental feature of every aspect of the universe is change. Whilst Parmenides argued from the fact of ceaseless change in nature to a metaphysical conception of the world in which neither change nor plurality is real, Anaxagoras left aside metaphysics and attempted to explain the principles of change and the maintenance of multiplicity. He did accept the sheer logic of the Parmenidean demonstration that nothing comes into being nor passes away and taught that change is due to separation and combination.
Matter for Anaxagoras is eternal and changeless in its essential nature. Since whatever is cannot cease to be, material substances cannot be reduced to fundamentally different elements. Therefore, matter must be infinitely varied in its irreducible parts to account for the vast variety of things that exist. The doctrine of homoiomeria is simply that the parts have the same nature as the whole, and the ultimate parts are eternal. Since living forms must be composed of parts of the same nature, and since they are nourished by food, every object must contain particles of an infinite variety and life must be part of everything that exists. Just as bone is called bone because of a predominance of bone particles, and rock is so named because of a predominance of mineral particles, so living things are recognized as such when the arrangement of particles allows for the expression of life. Given that "in everything there is a portion of everything", if material particles are of any size and of infinite variety, each thing, for example, a loaf of bread, would be infinite in size. If particles are of no size, however, even an infinite number would constitute no size at all. Therefore, Anaxagoras reasoned, particles are infinitesimal.
This ingenious view explains nutrition, for each part of the body extracts from ingested food that which is like itself, and it requires an infinitely large universe to accommodate an infinitude of particles. There is nothing in the nature of particles, though, that accounts for change. Particles are eternal, but structures composed of them come into existence and pass away. All change is the result of motion, and any rational theory of dynamics must aim to isolate one force or principle of motion which can account for every kind of change. Since the rational order of the universe includes change, the only rational entity which meets the required criteria is Nous or Mind. Materially, the macrocosm and microcosm reflect one another exactly; dynamically, the obvious operation of Nous in man, animals and even plants must reflect the universal operation of cosmic Mind. Mind as a rational principle of change manifests throughout nature as Law. Thus the universe consists of eternal, unchanging particulate matter and eternal, unchanging dynamic Mind. Subsequent philosophers criticized Anaxagoras for describing mechanical processes to explain natural phenomena and for not invoking Mind, but Anaxagoras saw clearly that calling on Mind as the direct cause of everything explained nothing, and that the universality of Mind implies that all mechanical processes are expressions of dynamic Nous. Mind, being as vast as the infinite cosmos, cannot be described in the language of secondary and derivative laws; nevertheless, being rational, it makes possible those describable laws whilst remaining an impenetrable yet undeniable mystery hidden behind them.
Whilst mechanistic explanations are sufficient for many natural phenomena, the laws involved cannot be thought of as simply mechanical. Law is the intelligent activity of Nous. Anaxagoras thought that this was shown by a study of perception. When two fluids of the same temperature are brought together, no alteration in temperature is observed. Only when qualitative opposites are conjoined does change occur. Perception involves change, and it too must follow the general principle that observable changes take place only between bodies whose states differ in some way. Universal Mind pervades every area of nature and is responsible for all change. Therefore Nous is qualitatively different from every material substance, and so is incorporeal yet substantial. This utter difference from everything else allows Mind to perceive and know everything. Nothing is hidden from Mind, which thus operates intelligently.
Armed with these principles of physics, Anaxagoras boldly set forth a theory of origins. Since everything contains everything else, differing only in preponderance of types of particles, Anaxagoras imagined that prior to the activity of Mind, matter abided in a state of chaos in which all particles were evenly distributed. Since nothing would differ from anything in this primordial condition, neither existence nor perception was possible, though matter and Mind were in a kind of timeless Be-Ness. For reasons now impossible to ascertain, Mind began to move matter in an initial rotational motion that tended to gather more dense particles at the centre and lighter particles in the extremes. The vestiges of this initial rotation can be seen in the movements of planets and the turning of the celestial vault. Once the rudimentary separation of material masses had occurred, a second motion, rising and falling, became dominant, as can be seen, Anaxagoras thought, in the convection currents which cause many meteorological phenomena. These motions produced the gross arrangement of the world as presently experienced, and Mind uses numerous more focalized processes to refine the world-order. Mind, being eternal as matter is, cannot perish. Whilst sleep is like death within a lifetime, there is one critical difference between the two.
Mind is immortal, but observation does not reveal its post-mortem destiny. For Anaxagoras, there is no reason to doubt that Mind continues to experience after the death of the body, remains involved in the ordering of the world, and ever reincarnates.
Since Anaxagoras refused to use Mind as a blanket explanation for every phenomenon, he had to construct explanations of diverse natural processes on the basis of observation and experimentation. Whilst some of his conclusions might appear to be absurd in comparison with contemporary explanations, his fidelity to his rigorous method led him to many remarkable insights. He held that all planets and stars are composed of the same substances of which the earth consists, and that they all follow the same laws. He recognized that thunder and lightning were effects of the same cause, which had to do with fiery etheric forces. He taught that light must travel in straight lines, that lunar eclipses are due to the earth's shadow falling on the moon, and that, unlike the sun which is incandescent, the moon shines by reflected sunlight. Long before Galileo dared to report his telescopic observation, Anaxagoras recognized that the moon is covered with mountains and ravines but is devoid of water. He taught that the Milky Way consists of innumerable stars and that the Nile floods in summer owing to far distant snows melting in the spring. Observation taught him that plants as well as animals breathe. He noted that in humans the father determines the sex of the child. So complete was his commitment to the unity of all life that he could not say the human being differs from animals because he possesses mind: all things are pervaded by Mind. Man is distinguished by his ability to express Nous more fully than other creatures, and this shows up in the human frame. When asked what the human hallmark is, Anaxagoras replied that "Men are the wisest of the animals because they have hands."
Anaxagoras not only exemplified the spirit of the Periclean age; he stood in the forefront of its creators. His faith in reason, reverence for Nature, rigour in method and refinement of experimental techniques earned him a permanent place as one of the early founders of modern science. Because Nous suffused everything, for Anaxagoras the ethical dimension of life is inherent in it, and so he gave no special attention to the subject. Plato saw that ethics had to be made explicit in a society rapidly losing its nearness to Nature, and that Mind in Man, psychology, is also a central study. In refraining from focussing on these critical areas of human understanding, Anaxagoras also adopted an attitude of true scepticism, neither pronouncing upon nor claiming to know anything about them other than that rational enquiry of the loftiest and most precise kind would lead to knowledge here as everywhere else. Whereupon he did focus his gaze, he influenced all subsequent generations of seekers, both in his theoretical methodology and in the experimental practices he laid down. Perhaps it is fitting that historians and philosophers nicknamed him 'Mind'.