Anaxagoras was born at Clazomenae in Asia Minor about 500 B.C. He was a man of noble family, and possessed considerable property. He neglected his property in the search for knowledge and in the pursuit of science and philosophy. Leaving his home at Clazomenae, he settled down in Athens. We have not heard so far anything of Athens in the history of Greek Philosophy. It was Anaxagoras who transplanted philosophy to Athens, which from his time forward became the chief centre of Greek thought. At Athens, Anaxagoras came into contact with all the famous men of the time. He was an intimate friend of Pericles, the statesman, and of Euripides, the poet. But his friendship with Pericles cost him dear. There was a strong political faction opposed to Pericles. So far as we know Anaxagoras never meddled in politics, but he was a friend of the statesman Pericles, and that was quite enough. The enemies of Pericles determined to teach Anaxagoras a lesson, and a charge of atheism and blasphemy was accordingly brought against him. The particulars of the charge were that Anaxagoras said that the sun was a red-hot stone, and that the moon was made of earth. This was quite true, as that is exactly what Anaxagoras did say of the sun and the moon. But the Greeks [{95}] regarded the heavenly bodies as gods; even Plato and Aristotle thought that the stars were divine beings. To call the sun a red-hot stone, and to say that the moon was made of earth, was therefore blasphemy according to Greek ideas. Anaxagoras was charged, tried, and condemned. The details of the trial, and of what followed, are not known with accuracy. But it appears that Anaxagoras escaped, probably with the help of Pericles, and from Athens went back to his native country in Asia Minor. He settled at Lampsacus, and died there at the age of 72. He was the author of a treatise in which he wrote down his philosophical ideas. This treatise was well-known at the time of Socrates, but only fragments now remain.
The foundation of the philosophy of Anaxagoras is the same as that of Empedocles and the Atomists. He denied any absolute becoming in the strict sense of the passing of being into not-being and not-being into being. Matter is uncreated and indestructible, and all becoming must be accounted for by the mixing and unmixing of its component parts. This principle Anaxagoras himself expressed with great clearness, in a fragment of his treatise which has come down to us. "The Greeks," he says, "erroneously assume origination and destruction, for nothing originates and nothing is destroyed. All is only mixed and unmixed out of pre-existent things, and it were more correct to call the one process composition and the other process decomposition."
The Atomists had assumed the ultimate constituents of things to be atoms composed of the same kind of matter. Empedocles had believed in four ultimate and underived kinds of matter. With neither of these does Anaxagoras agree. For him, all the different kinds of [{96}] matter are equally ultimate and underived, that is to say, such things as gold, bone, hair, earth, water, wood, etc., are ultimate kinds of matter, which do not arise from anything else, and do not pass over into one another. He also disagrees with the conception of the Atomists that if matter is divided far enough, ultimate and indivisible particles will be reached. According to Anaxagoras matter is infinitely divisible. In the beginning all these kinds of matter were mixed together in a chaotic mass. The mass stretches infinitely throughout space. The different kinds of matter wholly intermingle and interpenetrate each other. The process of world-formation is brought about by the unmixing of the conglomeration of all kinds of matter, and the bringing together of like matter with like. Thus the gold particles separating out of the mass come together, and form gold; the wood particles come together and form wood, and so on. But as matter is infinitely divisible and the original mixing of the elements was complete, they were, so to speak, mixed to an infinite extent. Therefore the process of unmixing would take infinite time, is now going on, and will always go on. Even in the purest element there is still a certain admixture of particles of other kinds of matter. There is no such thing as pure gold. Gold is merely matter in which the gold particles predominate.
As with Empedocles and the Atomists, a moving force is required to explain the world-process of unmixing. What, in the philosophy of Anaxagoras, is this force? Now up to the present point the philosophy of Anaxagoras does not rise above the previous philosophies of Empedocles and the Atomists. On the contrary, in clearness [{97}] and logical consistency, it falls considerably below the teaching of the latter. But it is just here, on the question of the moving force, that Anaxagoras becomes for the first time wholly original, and introduces a principle peculiar to himself, a principle, moreover, which is entirely new in philosophy. Empedocles had taken as his moving forces, Love and Hate, mythical and fanciful on the one hand, and yet purely physical on the other. The forces of the Atomists were also completely material. But Anaxagoras conceives the moving force as wholly non-physical and incorporeal. It is called Nous, that is, mind or intelligence. It is intelligence which produces the movement in things which brings about the formation of the world. What was it, now, which led Anaxagoras to the doctrine of a world-governing intelligence? It seems that he was struck with the apparent design, order, beauty and harmony of the universe. These things, he thought, could not be accounted for by blind forces. The world is apparently a rationally governed world. It moves towards definite ends. Nature shows plentiful examples of the adaptation of means to ends. There appears to be plan and purpose in the world. The Atomists had assumed nothing but matter and physical force. How can design, order, harmony and beauty be brought about by blind forces acting upon chaotic matter? Blind forces acting upon a chaos would produce motion and change. But the change would be meaningless and purposeless. They could not produce a rationally ordered cosmos. One chaos would succeed another chaos ad infinitum. That alone which can produce law and order is intelligence. There must therefore be a world-controlling Nous.
What is the character of the Nous, according to Anaxagoras? Is it, in the first place, really conceived as purely non-material and incorporeal? Aristotle, who was in a position to know more of the matter than any modern scholar, clearly implies in his criticism that the Nous of Anaxagoras is an incorporeal principle, and he has been followed in this by the majority of the best modern writers, such as Zeller and Erdmann. But the opposite view has been maintained, by Grote, for example, and more recently by Professor Burnet, who thinks that Anaxagoras conceived the Nous as a material and physical force. [Footnote 8] As the matter is of fundamental importance, I will mention the chief arguments upon which Professor Burnet rests his case. In the first place Anaxagoras described the Nous as the "thinnest and purest of all things." He also said that it was "unmixed," that it had in it no mixture of anything besides itself. Professor Burnet argues that such words as "thin" and "unmixed" would be meaningless in connection with an incorporeal principle. Only material things can properly be described as thin, pure, and unmixed. Secondly, Professor Burnet thinks that it is quite certain that the Nous occupies space, for Anaxagoras speaks of greater and smaller portions of it. Greater and smaller are spatial relations. Hence the Nous occupies space, and that which occupies space is material. But surely these are very inconclusive arguments. In the first place as regards the use of the words "thin" and "unmixed." It is true that these terms express primarily physical qualities. But, as I pointed out in [{99}] the first chapter, almost all words by which we seek to express incorporeal ideas have originally a physical signification. And if Anaxagoras is to be called a materialist because he described the Nous as thin, then we must also plead guilty to materialism if we say that the thought of Plato is "luminous," or that the mind of Aristotle is "clear." The fact is that all philosophy labours under the difficulty of having to express non-sensuous thought in language which has been evolved for the purpose of expressing sensuous ideas. There is no philosophy in the world, even up to the present day, in which expressions could not be found in plenty which are based upon the use of physical analogies to express entirely non-physical ideas. Then as regards the Nous occupying space, it is not true that greater and smaller are necessarily spatial relations. They are also qualitative relations of degree. I say that the mind of Plato is greater than the mind of Callias. Am I to be called a materialist? Am I to be supposed to mean that Plato's mind occupies more space than that of Callias? And it is certainly in this way that Anaxagoras uses the terms. "All Nous," he says, "is alike, both the greater and the smaller." He means thereby that the world-forming mind (the greater) is identical in character with the mind of man (the smaller). For Anaxagoras it is the one Nous which animates all living beings, men, animals, and even plants. These different orders of beings are animated by the same Nous but in different degrees, that of man being the greatest. But this does not mean that the Nous in man occupies more space than the Nous in a plant. But even if Anaxagoras did conceive the Nous as spatial, it does not follow that he [{100}] regarded it as material. The doctrine of the non-spatiality of mind is a modern doctrine, never fully developed till the time of Descartes. And to say that Anaxagoras did not realize that mind is non-spatial is merely to say that he lived before the time of Descartes. No doubt it would follow from this that the incorporeality of mind is vaguely and indistinctly conceived by Anaxagoras, that the antithesis between matter and mind is not so sharply drawn by him as it is by us. But still the antithesis is conceived, and therefore it is correct to say that the Nous of Anaxagoras is an incorporeal principle. The whole point of this introduction of the Nous into the philosophy of Anaxagoras is because he could not explain the design and order of the universe on a purely physical basis.
[Footnote 8: Early Greek Philosophy, chap. vi. § 132.]
The next characteristic of Nous is that it is to be thought of as essentially the ground of motion. It is because he cannot in any other way explain purposive motion that Anaxagoras introduces mind into his otherwise materialistic system. Mind plays the part of the moving force which explains the world-process of unmixing. As the ground of motion, the Nous is itself unmoved; for if there were any motion in it we should have to seek for the ground of this motion in something else outside it. That which is the cause of all motion, cannot itself be moved. Next, the Nous is absolutely pure and unmixed with anything else. It exists apart, by itself, wholly in itself, and for itself. In contrast to matter, it is uncompounded and simple. It is this which gives it omnipotence, complete power over everything, because there is no mixture of matter in it to limit it, to clog and hinder its activities. We moderns are [{101}] inclined to ask the question whether the Nous is personal. Is it, for example, a personal being like the God of the Christians? This is a question which it is almost impossible to answer. Anaxagoras certainly never considered it. According to Zeller, the Greeks had an imperfect and undeveloped conception of personality. Even in Plato we find the same difficulty. The antithesis between God as a personal and as an impersonal being, is a wholly modern idea. No Greek ever discussed it.
To come now to the question of the activity of the Nous and its function in the philosophy of Anaxagoras, we must note that it is essentially a world-forming, and not a world-creating, intelligence. The Nous and matter exist side by side from eternity. It does not create matter, but only arranges it. "All things were together," says Anaxagoras, "infinitely numerous, infinitely little; then came the Nous and set them in order." In this Anaxagoras showed a sound logical sense. He based his idea of the existence of Nous upon the design which exhibits itself in the world. In modern times the existence of design in the world has been made the foundation of an argument for the existence of God, which is known as the teleological argument. The word teleology means the view of things as adapting means towards purposive ends. To see intelligent design in the universe is to view the universe teleologically. And the teleological argument for the existence of God asserts that, as there is evidence of purpose in nature, this must be due to an intelligent cause. But, as a matter of fact, taken by itself, teleology cannot possibly be made the basis of an argument for the existence of a world-creating intelligence, but only for the existence of a world-designing [{102}] intelligence. If you find in the desert the ruins of ancient cities and temples, you are entitled to conclude therefrom, that there existed a mind which designed these cities and buildings, and which arranged matter in that purposive way, but you are not entitled to conclude that the mind which designed the cities also created the matter out of which they were made. Anaxagoras was, therefore, in that sense quite right. Teleology is not evidence of a world-creating mind, and if we are to prove that, we must have recourse to other lines of reasoning.
In the beginning, then, there was a chaotic mixture of different kinds of matter. The Nous produced a vortex at one point in the middle of this mass. This vortex spread itself outwards in the mass of matter, like rings caused by the fall of a stone in water. It goes on for ever and continually draws more and more matter out of the infinite mass into itself. The movement, therefore, is never-ending. It causes like kinds of matter to come together with like, gold to gold, wood to wood, water to water, and so on. It is to be noted, therefore, that the action of the Nous is apparently confined to the first movement. It acts only at the one central point, and every subsequent movement is caused by the vortex itself, which draws in more and more of the surrounding matter into itself. First are separated out the warm, dry, and light particles, and these form the aether or upper air. Next come the cold, moist, dark, and dense particles which form the lower air. Rotation takes the latter towards the centre, and out of this the earth is formed. The earth, as with Anaximenes, is a flat disc, borne upon the air. The heavenly bodies consist of [{103}] masses of stone which have been torn from the earth by the force of its rotation, and being projected outwards become incandescent through the rapidity of their movement. The moon is made of earth and reflects the light of the sun. Anaxagoras was thus the first to give the true cause of the moon's light. He was also the first to discover the true theory of eclipses, since he taught that the solar eclipse is due to the intervention of the moon between the sun and the earth, and that lunar eclipses arise from the shadow of the earth falling upon the moon. He believed that there are other worlds besides our own with their own suns and moons. These worlds are inhabited. The sun, according to Anaxagoras, is many times as large as the Peloponnese. The origin of life upon the earth is accounted for by germs which existed in the atmosphere, and which were brought down into the terrestrial slime by rain water, and there fructified. Anaxagoras's theory of perception is the opposite of the theories of Empedocles and the Atomists. Perception takes place by unlike matter meeting unlike.