Essays on Ancient Greek Philosophy

John Burnet's Early Greek Philosophy:
Chapter 6: Anaxagoras of Clazomenae

120. Date

All that Apollodorus tells us with regard to the date of Anaxagoras seems to rest on the authority of Demetrius Phalereus, who said of him, in his Register of Archons, that he "began to be a philosopher" at Athens at the age of twenty, in the archonship of Callias or Calliades (480-79 B.C.). This date was probably derived from a calculation based on the philosopher's age at the time of his trial, which Demetrius had every opportunity of learning from sources no longer extant. Apollodorus inferred that Anaxagoras was born in 01. LXX. (500-496 B.C.), and he adds that he died at the age of seventy-two in 01. LXXXVIII. I (428-27 B.C.). He doubtless thought it natural that he should not survive Pericles, and that he should die the year Plato was born. We have a further statement, of doubtful origin, but probably due also to Demetrius, that Anaxagoras lived at Athens for thirty years. If it is correct, we get from about 480 to 450 B.C. as the time he lived there.

There can be no doubt that these dates are very nearly right. Aristotle tells us that Anaxagoras was older than Empedocles, who was probably born before 490 B.C. (§ 98); and Theophrastus said that Empedocles was born "not long after Anaxagoras." Democritus, too, said that he himself was a young man in the old age of Anaxagoras, and he must have been born about 460 B.C.

121. Early Life

Anaxagoras was from Clazomenae, and Theophrastus tells us that his father's name was Hegesibulus. The tradition was that he neglected his possessions to follow science. It is certain, at any rate, that already in the fourth century he was regarded as the type of the man who leads the "theoretic life." Of course the story of his contempt for worldly goods was seized on later by the historical novelist and tricked out with the usual apophthegms. These do not concern us here.

One incident belonging to the early manhood of Anaxagoras is recorded, namely, the fall of a huge meteoric stone into the Aegospotami in 468-67 B.C. Our authorities tell us he predicted this phenomenon, which is plainly absurd. But we shall see reason to believe that it may have occasioned one of his most striking departures from the earlier cosmology, and led to his adoption of the very view for which he was condemned at Athens. At all events, the fall of the stone made a profound impression at the time, and it was still shown to tourists in the days of Pliny and Plutarch.

122. Relation to the Ionic School

The doxographers speak of Anaxagoras as the pupil of Anaximenes. This can hardly be correct; Anaximenes most probably died before Anaxagoras was born. But it is not enough to say that the statement arose from the fact that the name of Anaxagoras followed that of Anaximenes in the Successions. We have its original source in a fragment of Theophrastus himself, which states that Anaxagoras had been "an associate of the philosophy of Anaximenes." Now this expression has a very distinct meaning if we accept the view as to "schools" of science set forth in the Introduction (§ XIV). It means that the old Ionic school survived the destruction of Miletus in 494 B.C., and continued to flourish in the other cities of Asia. It means, further, that it produced no man of distinction after its third great representative, and that "the philosophy of Anaximenes" was still taught by whoever was now at the head of the society.

At this point, then, it may be well to indicate briefly the conclusions we shall come to in the next few chapters with regard to the development of philosophy during the first half of the fifth century B.C. We shall find that, while the old Ionic school was still capable of training great men, it was now powerless to keep them. Anaxagoras went his own way; Melissus and Leucippus, though they still retained enough of the old views to bear witness to the source of their inspiration, were too strongly influenced by the Eleatic dialectic to remain content with the theories of Anaximenes. It was left to second-rate minds like Diogenes to champion the orthodox system, while third-rate minds like Hippon of Samos went back to the cruder theory of Thales. The details of this anticipatory sketch will become clearer as we go on; for the present, it is only necessary to call the reader's attention to the fact that the old Ionic Philosophy now forms a sort of background to our story, just as Orphic and Pythagorean religious ideas have done in the preceding chapters.

123. Anaxagoras at Athens

Anaxagoras was the first philosopher to take up his abode at Athens. We are not informed what brought him there in the year of Salamis. He was, however, a Persian subject; for Clazomenae had been reduced after the suppression of the Ionian Revolt, and it seems likely enough that he was in the Persian army.

Anaxagoras is said to have been the teacher of Pericles, and the fact is placed beyond the reach of doubt by the testimony of Plato. In the Phaedrus he makes Socrates say: "For all arts that are great, there is need of talk and discussion on the parts of natural science that deal with things on high; for that seems to be the source which inspires high-mindedness and effectiveness in every direction. Pericles added this very acquirement to his original gifts. He fell in, it seems, with Anaxagoras, who was a scientific man; and, satiating himself with the theory of things on high, and having attained to a knowledge of the true nature of mind and intellect, which was just what the discourses of Anaxagoras were mainly about, he drew from that source whatever was of a nature to further him in the art of speech." This clearly means that Pericles associated with Anaxagoras before he became a prominent politician. So too Isocrates says that Pericles was the pupil of two "sophists," Anaxagoras and Damon. There can be no doubt that the teaching of Damon belongs to the youth of Pericles, and it is to be inferred that the same is true of that of Anaxagoras.

A more difficult question is the alleged relation of Euripides to Anaxagoras. The oldest authority for it is Alexander of Aitolia, poet and librarian, who lived at the court of Ptolemy Philadelphus (c. 280 B.C.). He referred to Euripides as the "nursling of brave Anaxagoras." The famous fragment on the blessedness of the scientific life might just as well refer to any other cosmologist as to Anaxagoras, and indeed suggests more naturally a thinker of a more primitive type. On the other hand, it is likely enough that Anaxagoras did not develop his system all at once, and he doubtless began by teaching that of Anaximenes. Besides there is one fragment which distinctly expounds the central thought of Anaxagoras, and could hardly be referred to anyone else.

124. The Trial

It is clear that, if we adopt the chronology of Demetrius of Phalerum, the trial of Anaxagoras must be placed early in the political career of Pericles. That is the tradition preserved by Satyrus, who says that the accuser was Thucydides, son of Melesias, and that the charge was impiety and Medism. As Thucydides was ostracized in 443 B.C., that would make it probable that the trial of Anaxagoras took place about 450 B.C., and would bring it into connection with the ostracism of the other teacher of Pericles, Damon. If that is so, we understand at once why Plato never makes Socrates meet with Anaxagoras. He had handed his school over to Archelaus before Socrates was old enough to take an interest in scientific theories. We do learn from Plato, however, what the charge of impiety was based on. It was that Anaxagoras taught the sun was a red-hot stone, and the moon earth, and we shall see that he certainly did hold these views (§ 133). For the rest, the most likely account is that he was got out of prison and sent away by Pericles. We know that such things were possible at Athens.

Driven from his adopted home, Anaxagoras naturally went back to Ionia, where at least he would be free to teach what he pleased. He settled at Lampsacus, a colony of Miletus, and we shall see reason to believe that he founded a school there. If so, he must have lived at Lampsacus for some time before his death. The Lampsacenes erected an altar to his memory in their market-place, dedicated to Mind and Truth; and the anniversary of his death was long kept as a holiday for school-children, it was said at his own request.

125. Writings

Diogenes includes Anaxagoras in his list of philosophers who left only a single book, and he has also preserved the accepted criticism of it, namely, that it was written "in a lofty and agreeable style." There is no evidence of any weight to set against this testimony, which comes ultimately from the librarians of Alexandria. The story that Anaxagoras wrote a treatise on perspective as applied to scene painting is most improbable; and the statement that he composed a work dealing with the quadrature of the circle is a misunderstanding of an expression in Plutarch. We learn from the passage in the Apology, referred to above, that the works of Anaxagoras could be bought at Athens for a drachma; and that the book was of some length may be gathered from the way in which Plato makes Socrates go on to speak of it. In the sixth century A.D. Simplicius had access to a copy, doubtless in the library of the Academy; and it is to him we owe the preservation of all our fragments, with one or two very doubtful exceptions. Unfortunately his quotations seem to be confined to the First Book, that dealing with general principles, so that we are left somewhat in the dark as to the treatment of details.

126. The Fragments

I give the fragments according to the text and arrangement of Diels:

(1) All things were together, infinite both in number and in smallness; for the small too was infinite. And, when all things were together, none of them could be distinguished for their smallness. For air and aether prevailed over all things, being both of them infinite; for amongst all things these are the greatest both in quantity and size. R. P. 151.

(2) For air and aether are separated off from the mass that surrounds the world, and the surrounding mass is infinite in quantity. R. P. ib.

(3) Nor is there a least of what is small, but there is always a smaller; for it cannot be that what is should cease to be by being cut. But there is also always something greater than what is great, and it is equal to the small in amount, and, compared with itself, each thing is both great and small. R. P. 159 a.

(4) And since these things are so, we must suppose that there are contained many things and of all sorts in the things that are uniting, seeds of all things, with all sorts of shapes and colors and savors (R. P. ib.), and that men have been formed in them, and the other animals that have life, and that these men have inhabited cities and cultivated fields as with us; and that they have a sun and a moon and the rest as with us; and that their earth brings forth for them many things of all kinds of which they gather the best together into their dwellings, and use them (R. P. 160 b). Thus much have I said with regard to separating off, to show that it will not be only with us that things are separated off, but elsewhere too.

But before, they were separated off, when all things were together, not even was any color distinguishable: for the mixture of all things prevented it -- of the moist and the dry, and the warm and the cold, and the light and the dark, and of much earth that was in it, and of a multitude of innumerable seeds in no way like each other. For none of the other things either is like any other. And these things being so, we must hold that all things are in the whole. R. P. 151.

(5) And those things having been thus decided, we must know that all of them are neither more nor less; for it is not possible for them to be more than all, and all are always equal. R. P. 151.

(6) And since the portions of the great and of the small are equal in amount, for this reason, too, all things will be in everything; nor is it possible for them to be apart, but all things have a portion of everything. Since it is impossible for there to be a least thing, they cannot be separated, nor come to be by themselves; but they must be now, just as they were in the beginning, all together. And in all things many things are contained, and an equal number both in the greater and in the smaller of the things that are separated off.

(7) ... So that we cannot know the number of the things that are separated off, either in word or deed.

(8) The things that are in one world are not divided nor cut off from one another with a hatchet, neither the warm from the cold nor the cold from the warm. R. P. 155 e.

(9) ... as these things revolve and are separated off by the force and swiftness. And the swiftness makes the force. Their swiftness is not like the swiftness of any of the things that are now among men, but in every way many times as swift.

(10) How can hair come from what is not hair, or flesh from what is not flesh? R. P. 155, f, n. I.

(11) In everything there is a portion of everything except Nous, and there are some things in which there is Nous also. R. P. 160 b.

(12) All other things partake in a portion of everything, while Nous is infinite and self-ruled, and is mixed with nothing, but is alone, itself by itself. For if it were not by itself, but were mixed with anything else, it would partake in all things if it were mixed with any; for in everything there is a portion of everything, as has been said by me in what goes before, and the things mixed with it would hinder it, so that it would have power over nothing in the same way that it has now being alone by itself. For it is the thinnest of all things and the purest, and it has all knowledge about everything and the greatest strength; and Nous has power over all things, both greater and smaller, that have life. And Nous had power over the whole revolution, so that it began to revolve in the beginning. And it began to revolve first from a small beginning; but the revolution now extends over a larger space, and will extend over a larger still. And all the things that are mingled together and separated off and distinguished are all known by Nous. And Nous set in order all things that were to be, and all things that were and are not now and that are, and this revolution in which now revolve the stars and the sun and the moon, and the air and the aether that are separated off. And this revolution caused the separating off, and the rare is separated off from the dense, the warm from the cold, the light from the dark, and the dry from the moist. And there are many portions in many things. But no thing is altogether separated off nor distinguished from anything else except Nous. And all Nous is alike, both the greater and the smaller; while nothing else is like anything else, but each single thing is and was most manifestly those things of which it has most in it. R. P. 155.

(13) And when Nous began to move things, separating off took place from all that was moved, and so much as Nous set in motion was all separated. And as things were set in motion and separated, the revolution caused them to be separated much more.

(14) And Nous, which ever is, is certainly there, where everything else is, in the surrounding mass, and in what has been united with it and separated off from it.

(15) The dense and the moist and the cold and the dark came together where the earth is now, while the rare and the warm and the dry (and the bright) went out towards the further part of the aether. R. P. 156.

(16) From these as they are separated off earth is solidified for from mists water is separated off, and from water earth. From the earth stones are solidified by the cold, and these rush outwards more than water. R. P. 156.

(17) The Hellenes follow a wrong usage in speaking of coming into being and passing away; for nothing comes into being or passes away, but there is mingling and separation of things that are. So they would be right to call coming into being mixture, and passing away separation. R. P. 150.

(18) It is the sun that puts brightness into the moon.

(19) We call rainbow the reflection of the sun in the clouds. Now it is a sign of storm; for the water that flows round the cloud causes wind or pours down in rain.

(20) With the rise of the Dogstar (?) men begin the harvest; with its setting they begin to till the fields. It is hidden for forty days and nights.

(21) From the weakness of our senses we are not able to judge the truth.

(21a) What appears is a vision of the unseen.

(21b) (We can make use of the lower animals) because we use our own experience and memory and wisdom and art.

(22) What is called "birds' milk" is the white of the egg.

127. Anaxagoras and His Predecessors

The system of Anaxagoras, like that of Empedocles, aimed at reconciling the Eleatic doctrine that corporeal substance is unchangeable with the existence of a world which everywhere presents the appearance of coming into being and passing away. The conclusions of Parmenides are frankly accepted and restated. Nothing can be added to all things; for there cannot be more than all, and all is always equal (fr. 5). Nor can anything pass away. What men commonly call coming into being and passing away is really mixture and separation (fr. 17).

It is in every way probable that Anaxagoras derived his theory of mixture from his younger contemporary, whose poem may have been published before his own treatise. In any case, we have seen that the opinions of the latter were known at Athens before the middle of the fifth century. We have seen how Empedocles sought to save the world of appearance by maintaining that the opposites -- hot and cold, moist and dry -- were things, each one of which was real in the Parmenidean sense. Anaxagoras regarded this as inadequate. Everything changes into everything else, the things of which the world is made are not "cut off with a hatchet" (fr. 8) in this way. On the contrary, the true formula must be: There is a portion of everything in everything (fr. 11).

128. "Everything in Everything"

A part of the argument by which Anaxagoras sought to prove this point has been preserved in a corrupt form by Aetius, and Diels has recovered some of the original words from the scholiast on St. Gregory Nazianzene. "We use a simple nourishment," he said, "when we eat the fruit of Demeter or drink water. But how can hair be made of what is not hair, or flesh of what is not flesh?" (fr. 10). That is just the sort of question the early Milesians must have asked, only the physiological interest has now definitely replaced the meteorological. We shall find a similar train of reasoning in Diogenes of Apollonia (fr. 2).

The statement that there is a portion of everything in everything, is not to be understood as referring simply to the original mixture of things before the formation of the worlds (fr. 1). On the contrary, even now "all things are together," and everything, however small and however great, has an equal number of "portions" (fr. 6). A smaller particle of matter could only contain a smaller number of portions, if one of those portions ceased to be; but if anything is, in the full Parmenidean sense, it is impossible that mere division should make it cease to be (fr. 3). Matter is infinitely divisible; for there is no least thing, any more than there is a greatest. But however great or small a body may be, it contains just the same number of "portions," that is, a portion of everything.

129. The Portions

What are these "things" of which everything contains a portion? It once was usual to represent the theory of Anaxagoras as if he had said that wheat, for instance, contained small particles of flesh, blood, bones, and the like; but we have just seen that matter is infinitely divisible (fr. 3), and that there are as many "portions" in the smallest particle as in the greatest (fr. 6). That is fatal to the old view. However far we carry division, we can never reach anything "unmixed," so there can be no such thing as a particle of simple nature, however minute.

This difficulty can only be solved in one way. In fr. 8 the examples given of things which are not "cut off from one another with a hatchet" are the hot and the cold; and elsewhere (frs. 4, 15), mention is made of the other traditional "opposites." Aristotle says that, if we suppose the first principles to be infinite, they may either be one in kind, as with Democritus, or opposite. Simplicius, following Porphyry and Themistius, refers the latter view to Anaxagoras; and Aristotle himself implies that the opposites of Anaxagoras had as much right to be called first principles as the homoeomeries."

It is of those opposites, then, and not of the different forms of matter; that everything contains a portion. Every particle, however large or however small, contains every one of those opposite qualities. That which is hot is also to a certain extent cold. Even snow, Anaxagoras affirmed, was black; that is, even the white contains a certain portion of the opposite quality. It is enough to indicate the connection of this with the views of Heraclitus (§ 80).

130. Seeds

The difference, then, between the theory of Anaxagoras and that of Empedocles is this. Empedocles had taught that, if you divide the various things which make up this world, and in particular the parts of the body, such as flesh, bones, and the like, far enough, you come to the four "roots" or elements, which are, accordingly, the ultimate reality. Anaxagoras held that, however far you may divide any of these things -- and they are infinitely divisible -- you never come to a part so small that it does not contain portions of all the opposites. On the other hand, everything can pass into everything else just because the "seeds," as he called them, of each form of matter contain a portion of everything, that is, of all the opposites, though in different proportions. If we are to use the word "element" at all, it is these seeds that are the elements in the system of Anaxagoras.

Aristotle expresses this by saying that Anaxagoras regards the homoiomerê as stoicheia. We have seen that the term stoicheion is of later date than Anaxagoras, and it is natural to suppose that the word homoiomerê is also only Aristotle's name for the "seeds." In his own system, the homoiomerê are intermediate between the elements (stoicheia), of which they are composed, and the organs (organa), which are composed of them. The heart cannot be divided into hearts, but the parts of flesh are flesh. That being so, Aristotle's statement is quite intelligible from his own point of view, but there is no reason for supposing that Anaxagoras expressed himself in that particular way. All we are entitled to infer is that he said the "seeds," which he substituted for the "roots" of Empedocles, were not the opposites in a state of separation, but each contained a portion of them all. If Anaxagoras had used the term "homoeomeries" himself, it would be very strange that Simplicius should quote no fragment containing it.

The difference between the two systems may also be regarded from another point of view. Anaxagoras was not obliged by his theory to regard the elements of Empedocles as primary, a view to which there were obvious objections, especially in the case of earth. He explained them in quite another way. Though everything has a portion of everything in it, things appear to be that of which there is most in them (fr. 12 sub fin.). We may say, then, that Air is that in which there is most cold, Fire that in which there is most heat, and so on, without giving up the view that there is a portion of cold in the fire and a portion of heat in the air. The great masses which Empedocles had taken for elements are really vast collections of all manner of "seeds." Each of them is, in fact, a panspermia.

131. "All Things Together"

From all this it follows that, when "all things were together," and when the different seeds of things were mixed together in infinitely small particles (fr. 1), the appearance presented would be that of one of what had hitherto been regarded as the primary substances. As a matter of fact, they did present the appearance of "air and aether"; for the qualities (things) which belong to these -- i.e. the hot and the cold, prevail in quantity over all other things in the universe, and everything is most obviously that of which it has most in it (fr. 12 sub fin.). Here, then, Anaxagoras attaches himself to Anaximenes. The primary condition of things, before the formation of the worlds, is much the same in both; only, with Anaxagoras, the original mass is no longer the primary substance, but a mixture of innumerable seeds divided into infinitely small parts.

This mass is infinite, like the air of Anaximenes, and it supports itself, since there is nothing surrounding it. Further, the "seeds" of all things which it contains are infinite in number (fr. 1). But, as the innumerable seeds may be divided into those in which the portions of cold, moist, dense, and dark prevail, and those which have most of the warm, dry, rare, and light in them, we may say that the original mass was a mixture of infinite Air and of infinite Fire. The seeds of Air, of course, contain portions of the "things" that predominate in Fire, and vice versa; but we regard everything as being that of which it has most in it. Lastly, there is no void in this mixture, an addition to the theory made necessary by the arguments of Parmenides. It is, however, worthy of note that Anaxagoras added an experimental proof of this to the purely dialectical one of the Eleatics. He used the klepsydra experiment as Empedocles had done (fr. 100), and also showed the corporeal nature of air by means of inflated skins.

132. Nous

Like Empedocles, Anaxagoras required some external cause to produce motion in the mixture. Body, Parmenides had shown, would never move itself, as the Milesians had assumed. Anaxagoras called the cause of motion by the name of Nous. It was this which made Aristotle say that he "stood out like a sober man from the random talkers that had preceded him," and he has often been credited with the introduction of the spiritual into philosophy. The disappointment expressed by Socrates in the Phaedo as to the way in which Anaxagoras worked out the theory should, however, make us pause to reflect before accepting too exalted a view of it. Plato makes Socrates say: "I once heard a man reading a book, as he said, of Anaxagoras, and saying it was Mind that ordered the world and was the cause of all things. I was delighted to hear of this cause, and I thought he really was right.... But my extravagant expectations were all dashed to the ground when I went on and found that the man made no use of Mind at all. He ascribed no causal power whatever to if in the ordering of things, but to airs, and aethers, and waters, and a host of other strange things." Aristotle, of course with this passage in mind, says: "Anaxagoras uses Mind as a deus ex machine to account for the formation of the world; and whenever he is at a loss to explain why anything necessarily is, he drags it in. But in other cases he makes anything rather than Mind the cause." These utterances may well suggest that the Nous of Anaxagoras was something on the same level as the Love and Strife of Empedocles, and this will be confirmed when we look at what he has to say about it.

In the first place, Nous is unmixed (fr. 12), and does not, like other things, contain a portion of everything. This would hardly be worth saying of an immaterial mind; no one would suppose that to be hot or cold. The result of its being unmixed is that it "has power over" everything, that is to say, in the language of Anaxagoras, it causes things to move. Heraclitus had said as much of Fire, and Empedocles of Strife. Further, it is the "thinnest" of all things, so that it can penetrate everywhere, and it would be meaningless to say that the immaterial is "thinner" than the material. It is true that Nous also "knows all things"; but so, perhaps, did the Fire of Heraclitus, and certainly the Air of Diogenes. Zeller holds, indeed, that Anaxagoras meant to speak of something incorporeal; but he admits that he did not succeed in doing so, and that is historically the important point. Nous is certainly imagined as occupying space; for we hear of greater and smaller parts of it (fr. 12).

The truth probably is that Anaxagoras substituted Nous for the Love and Strife of Empedocles, because he wished to retain the old Ionic doctrine of a substance that "knows" all things, and, to identify that with the new theory of a substance that "moves" all things. Perhaps, too, it was his increased interest in physiological as distinguished from purely cosmological matters that led him to speak of Mind rather than Soul. The former word certainly suggests to the Greek an intimate connection with the living body which the latter does not. But, in any case, the originality of Anaxagoras lies far more in the theory of substance than in that of Nous.

133. Formation of the Worlds

The formation of a world starts with a rotatory motion which Nous imparts to a portion of the mixed mass in which "all things are together" (fr. 13), and this rotatory motion gradually extends over a wider and wider space. Its rapidity (fr. 9) produced a separation of the rare and the dense, the cold and the hot, the dark and the light, the moist and the dry (fr. 15). This separation produces two great masses, the one consisting mostly of the rare, hot, light, and dry, called the "Aether"; the other, in which the opposite qualities predominate, called "Air" (fr. 1). Of these the Aether or Fire took the outside while the Air occupied the center (fr. 15).

The next stage is the separation of the air into clouds, water, earth, and stones (fr. 16). In this Anaxagoras follows Anaximenes closely. In his account of the origin of the heavenly bodies, however, he showed himself more original. We read at the end of fr. 16 that stones "rush outwards more than water," and we learn from the doxographers that the heavenly bodies were explained as stones torn from the earth by the rapidity of its rotation and made red-hot by the speed of their own motion. Perhaps the fall of the meteoric stone at Aegospotami had something to do with the origin of this theory. It will also be observed that it necessarily implies the rotation of the flat earth along with the "eddy" (dinê).

134. Innumerable Worlds

That Anaxagoras adopted the ordinary Ionian theory of innumerable worlds is clear from fr. 4, which we have no right to regard as other than continuous. The words "that it was not only with us that things were separated off, but elsewhere too" can only mean that Nous has caused a rotatory movement in more parts of the boundless mixture than one. Aetius certainly includes Anaxagoras among those who held there was only one world; but this testimony cannot be considered of the same weight as that of the fragments. Zeller's reference of the words to the moon is very improbable. Is it likely that anyone would say that the inhabitants of the moon "have a sun and moon as with us"?

135. Cosmology

The cosmology of Anaxagoras is clearly based upon that of Anaximenes, as will be seen from a comparison of the following passage of Hippolytus with the quotations given in Chap. 1. (§ 29):

(3) The earth is flat in shape, and remains suspended because of its size and because there is no vacuum. For this reason the air is very strong, and supports the earth which is borne up by it.

(4) Of the moisture on the surface of the earth, the sea arose from the waters in the earth (for when these were evaporated the remainder turned salt), and from the rivers which flow into it.

(5) Rivers take their being both from the rains and from the waters in the earth; for the earth is hollow and has waters in its cavities. And the Nile rises in summer owing to the water that comes down from the snows in Ethiopia.

(6) The sun and the moon and all the stars are fiery stones carried round by the rotation of the aether. Under the stars are the sun and moon, and also certain bodies which revolve with them, but are invisible to us.

(7) We do not feel the heat of the stars because of the greatness of their distance from the earth; and, further, they are not so warm as the sun, because they occupy a colder region. The moon is below the sun, and nearer us.

(8) The sun surpasses the Peloponnesus in size. The moon has not a light of her own, but gets it from the sun. The course of the stars goes under the earth.

(9) The moon is eclipsed by the earth screening the sun's light from it, and sometimes, too, by the bodies below the moon coming before it. The sun is eclipsed at the new moon, when the moon screens it from us. Both the sun and the moon turn back in their courses owing to the repulsion of the air. The moon turns back frequently, because it cannot prevail over the cold.

(10) Anaxagoras was the first to determine what concerns the eclipses and the illumination of the sun and moon. And he said the moon was of earth, and had plains and ravines in it. The Milky Way was the reflection of the light of the stars that were not illuminated by the sun. Shooting stars were sparks, as it were, which leapt out owing to the motion of the heavenly vault.

(11) Winds arose when the air was rarefied by the sun, and when things were burned and made their way to the vault of heaven and were carried off. Thunder and lightning were produced by heat striking upon clouds.

(12) Earthquakes were caused by the air above striking on that beneath the earth; for the movement of the latter caused the earth which floats on it to rock.

All this confirms the statement of Theophrastus, that Anaxagoras had belonged to the school of Anaximenes. The flat earth floating on the air, the dark bodies below the moon, the explanation of the solstices and the "turnings back" of the moon by the resistance of air, the explanations of wind and of thunder and lightning, are all derived from the Milesian. As to the moon's light and the cause of eclipses, it was natural that Anaxagoras should be credited at Athens with these discoveries. On the other hand, it seems very unlikely that they were made by a believer in a flat earth, and there is sufficient evidence that they are really Pythagorean.

136. Biology

"There is a portion of everything in everything except Nous, and there are some things in which there is Nous also" (fr. 11). In these words Anaxagoras laid down the distinction between animate and inanimate things. He tells us that it is the same Nous that "has power over," that is, sets in motion, all things that have life, both the greater and the smaller (fr. 12). The Nous in living creatures is the same in all (fr. 12), and from this it followed that the different grades of intelligence we observe in the animal and vegetable worlds depend entirely on the structure of the body. The Nous was the same, but it had more opportunities in one body than another. Man was the wisest of animals, not because he had a better sort of Nous, but because he had hands. This is in accordance with the previous development of thought upon the subject. Parmenides, in his Second Part (fr. 16), had already made the thought of men depend on the constitution of their limbs.

As all Nous is the same, we are not surprised to find that plants were regarded as living creatures. If we may trust the pseudo-Aristotelian Treatise on Plants so far, Anaxagoras argued that they must feel pleasure and pain in connection with their growth and with the fall of their leaves. Plutarch says that he called plants "animals fixed in the earth."

Both plants and animals originated in the first instance from the panspermia. Plants arose when the seeds of them which the air contained were brought down by the rain-water, and animals originated in a similar way. Like Anaximander, Anaxagoras held that animals first arose in the moist elements

137. Perception

In these scanty notices we seem to see traces of a polemical attitude towards Empedocles, and the same may be observed in what we are told of the theory of perception adopted by Anaxagoras, especially in the view that perception is of contraries. The account which Theophrastus gives of this is as follows:

But Anaxagoras says that perception is produced by opposites; for like things cannot be effected by like. He attempts to give, a detailed enumeration of the particular senses. We see by means of the image in the pupil; but no image is cast upon what is of the same color, but only on what is different. With most living creatures things are of a different color to the pupil by day, though with some this is so by night, and these are accordingly keen-sighted at that time. Speaking generally, however, night is more of the same color with the eyes than day. And an image is cast on the pupil by day, because light is a concomitant cause of the image, and because the prevailing color casts an image more readily upon its opposite.

It is in the same way that touch and taste discern their objects. That which is just as warm or just as cold as we are neither warms us nor cools us by its contact; and, in the same way, we do not apprehend the sweet and the sour by means of themselves. We know cold by warm, fresh by salt, and sweet by sour, in virtue of our deficiency in each; for all these are in us to begin with. And we smell and hear in the same manner; the former by means of the accompanying respiration, the latter by the sound penetrating to the brain, for the bone which surrounds this is hollow, and it is upon it that the sound falls.

And all sensation implies pain, a view which would seem to be the consequence of the first assumption, for all unlike things produce pain by their contact. And this pain is made perceptible by the long continuance or by the excess of a sensation. Brilliant colors and excessive noises produce pain, and we cannot dwell long on the same things. The larger animals are the more sensitive, and, generally, sensation is proportionate to the size of the organs of sense. Those animals which have large, pure, and bright eyes, see large objects and from a great distance, and contrariwise.

And it is the same with hearing. Large animals can hear great and distant sounds, while less sounds pass unperceived; small animals perceive small sounds and those near at hand. It is the same too with smell. Rarefied air has more smell; for, when air is heated and rarefied, it smells. A large animal when it breathes draws in the condensed air along with the rarefied, while a small one draws in the rarefied by itself; so the large one perceives more. For smell is better perceived when it is near than when it is far by reason of its being more condensed, while when dispersed it is weak. But, roughly speaking, large animals do not perceive a rarefied smell, nor small animals a condensed one.

This theory marks in some respects an advance on that of Empedocles. It was a happy thought of Anaxagoras to make sensation depend upon irritation by opposites, and to connect it with pain. Many modern theories are based upon a similar idea.

That Anaxagoras regarded the senses as incapable of reaching the truth of things is shown by the fragments preserved by Sextus. But we must not, for all that, turn him into a sceptic. The saying preserved by Aristotle that "things are as we suppose them to be," has no value at all as evidence. It comes from some collection of apophthegms, not from the treatise of Anaxagoras himself; and it had, as likely as not, a moral application. He did say (fr. 21) that "the weakness of our senses prevents our discerning the truth," but this meant simply that we do not see the "portions" of everything which are in everything; for instance, the portions of black which are in the white. Our senses simply show us the portions that prevail. He also said that the things which are seen give us the power of seeing the invisible, which is the very opposite of scepticism (fr. 21a).