Ancient History & Civilisation



It makes sense to group Thales, Anaximander, and Anaximenes together, though the idea that they were a ‘school’, and formed master-pupil relationships, is certainly a distortion, based on the later desire to systematize which bedevils Presocratic studies in various ways. However, although Miletus was at the time a thriving city-state, it was small enough for all three of these thinkers to have known one another, and for each to have been acquainted with the others’ work and ideas. We can pinpoint Thales’ date fairly precisely, since we know he was alive at the time of a datable solar eclipse (T1; it was either the eclipse of 28 May 585 or that of 21 September 582 BCE), and it seems likely that the other two were younger contemporaries of his, with Anaximenes younger than Anaximander. If it is wondered why Miletus should have been so important in the history of philosophy, an adequate answer is given by considering its importance as a trade-route with links to the older cultures of Babylon, Egypt, Lydia, and Phoenicia. Ideas always travel with trade. The old civilizations had world-pictures and creation myths vastly different to anything the Greeks had come across. These startling and visionary ideas led a few Milesians to speculate for themselves. Miletus was a wealthy enough city for there to be a literate and leisured class.

The Milesian philosophers belong together because they—or at least Anaximander and Anaximenes, for whom we have just enough evidence—display in a primitive form the reductionist spirit discussed in the Introduction. They were trying to make the world comprehensible, which meant not only severely limiting the number and nature of the factors they used to explain phenomena, but also relying by and large on familiar features of the world, and, most importantly, introducing the idea of cosmic order or natural law. However, what this rather scientific summary of their work fails to capture is the grandeur and splendour of their geometric visions of the universe, which just barely emerge from behind the dry-as-dust writing of the doxographic tradition. In order to have a sense of the Milesian achievement, it is important always to bear the whole in mind, so as to avoid getting bogged down in the details. But this is not to say that the details were unimportant to them: as far as we can tell, they wanted to give a comprehensive picture and explanation of the whole universe, from the largest scale down to everyday phenomena such as rain and mist and rainbows. At the very birth of science and philosophy, the daring of this enterprise is breathtaking. Their distinctive approach is to explain things by looking to their origins, in a biological sense: the world arose by spontaneous generation out of more-or-less undifferentiated matter, which itself has the properties of life and growth.1

Our earliest witness to Thales’ activities regards him entirely as a practical man, an engineer rather than a speculative thinker (T2–3). Even the mathematical discoveries attributed to him are practical aids to drawing up an accurate calendar (T5) or navigation (T6). He soon became one of the ‘seven sages’ of Greece, to whom a number of pithy aphorisms were attributed; and in later times he became an archetype of the absentminded professor (e.g. T7). Nevertheless, there is enough evidence for us to be sure that he did come up with a more theoretical set of ideas, involving, above all, some reference to water (T8–10). It is very noticeable how hesitant Aristotle is when reporting any of Thales’ views, and we cannot know whether Aristotle was putting him in the correct protoscientific context or, as seems more likely, whether Thales was actually closer to a mythologer, claiming perhaps that the world emerged from a watery swamp at the beginning of time; there are parallels in both Egyptian and Babylonian creation myths. Perhaps he inferred from empirical observation that water was necessary for growth, and Aristotle imposed his own framework on this. Thales also seems to have formulated some kind of religious animism (T11). As for the eclipse, it is clear from Herodotus’ testimony (T1) that Thales did not exactly predict its occurrence, but knew (perhaps from Babylonian records), or more likely guessed, the year in which it was going to happen; however, in the later doxographic tradition this gradually becomes exaggerated, until we read (T4) of Thales having developed the ability to predict the exact occurrence of eclipses and other astronomical phenomena.2

If we can trust the report of later chroniclers that Anaximander died around 540, he was a younger contemporary of Thales. Again, as with Thales, we find him credited with practical scientific work (T12–13), most famously with drawing the first map of the world (which would have been as crudely symmetrical as the historian Herodotus complained at T14). Since Thales is also credited with the invention of the gnomon, and since it is likely that the Babylonians had been using the device for a long time, the report that Anaximander actually invented it is unreliable.

But apart from these practical achievements, Anaximander also speculated about the origins of the world (T15), claiming that it has its source in the boundless (apeiron, literally, ‘without limits’). Precisely what he meant by this ‘boundless’ is not clear, and perhaps he did not make it clear himself. Aristotle’s claim at T16 is unhelpful on this score, except to suggest that the boundless might actually have been something like infinite water or infinite air—in other words, that while it may have been boundless spatially (i.e. infinite), it was not indefinite qualitatively. This conforms with other early uses of the Greek word apeiros, but is contradicted by Aristotle’s own report elsewhere in Physics (T17), where it appears that Anaximander’s apeiron was a kind of mixture of opposites—i.e. with none of the oppositely qualified stuffs (early Greeks did not recognize qualities or predicates as distinct from stuffs) being distinct within it. It seems most likely that Anaximander himself said nothing definite about his boundless, seeing it as a spatially (and hence temporally) unlimited, homogeneous, material mass, and leaving Aristotle to fill in the gap in different ways at different times, and also to speculate as to Anaximander’s reasons for positing ‘the boundless’ as the source of all things (T18–20). We may catch a glimpse of Anaximander’s motivation in T15 and T19: if all the determinate stuffs of the universe, characterized as opposites, can change into one another, it would be wrong to privilege any particular determinate stuff over any other by making it the originating stuff of the universe.

T22 confirms the idea that the apeiron is qualitatively indefinite. If Anaximander felt the need to postulate a distinct immediate source for the qualities of the world—a kind of seed or germ that generates the opposites—this suggests that he wanted to preserve the qualitative indefiniteness of the apeiron itself. Of course, this raises as many problems as it solves: how does this ‘something productive of hot and cold’ separate off from the boundless, so that it is something distinct from the boundless? What is it for something to be ‘separated off’ from something else? At any rate, somehow (in an act which looks like little more than an abstraction of mythical masturbatory genesis by a single male god, especially since the word for ‘separate off‘can also mean ‘secrete’) the opposites, the basic elements which make up the world (chiefly, but not exclusively, hot and cold, wet and dry), emerged from the boundless (T15).

In T20 Aristotle seems to suggest that the boundless steers all things even now, in the manner of a purposeful or providential god. It is hard to see how this can be right for Anaximander, since the processes of the universe seem to take place by natural law, without any interference by this boundless god; but it may well be right that Anaximander conceived of the boundless as divine, and felt no need to explain the origin of change and the cosmogonic process because, qua divine, the boundless was instinct with life. The idea of natural law is contained in the one fragment of Anaximander, preserved in T15. There is constant interplay between the opposite stuffs of the world. Each is seen as giving offence to its opposite, and then as having to pay a penalty to it. At the onset of the hot season, for instance, the cool season gives way, or is overwhelmed by the hot, until it is its turn again. Neither is allowed by Time to commit the injustice of going on for too long.

The Greeks had long believed, except in their more pessimistic moments, that there was a law of compensation in human affairs—that the gods would, sooner or later, belittle a man who rose too high or too fast,3 but Anaximander extended this law to the world at large, making it a cosmic principle—and, importantly, one that was governed by ‘necessity’, an abstract, unchanging force, not a bunch of fickle gods. His vision of a universe ordered by cosmic justice was potent, and soon took hold of the Greek imagination. As the Athenian playwright Sophocles would put in the middle of the fifth century: ‘Even terrifying and the most mighty forces recognize rights. Winter with its snowdrifts yields to summer with its crops, and the weary round of night makes way for the white-horsed chariot of day, so that she may kindle her light’ (Ajax 669–73).

Another application of this principle of cosmic equilibrium may be glimpsed in T21. Anaximander seems to have believed that the earth was originally covered in water (flood myths are common all over the world, especially in the Middle East), but was drying out and would some day become entirely dry. Since the winds and the consequent motion of the heavenly bodies are also caused by this process of evaporation, at this point the universe would stop moving. This cosmic catastrophe would, we may guess, be followed by another deluge, and the whole process would start again. But these speculations should be tempered first by the fact that Aristotle himself, the source of T21, does not name Anaximander (it is only later sources who say that Aristotle had Anaximander in mind when writing this), and second by the fact that such complete flooding and drying out would contravene the principle Anaximander enunciates in his fragment, according to which none of the opposites is allowed to encroach too far. So perhaps Anaximander said that the world was subject to successive periods of increased and decreased sea-levels, which fall short of catastrophe.

In T15 Theophrastus attributes to Anaximander a belief in a plurality of worlds, without mentioning whether these are co-existent or successive. In fact, however, Theophrastus is probably wrong on this; given what we have seen about Anaximander’s cosmological views, there is no reason for him to posit the existence of more than just this world, which is held more or less in equilibrium for ever. Going back from the present state of the world to the cosmogonical process, it is clear that Anaximander went into some detail about the next stage (T22), which neatly allows him to explain the existence and nature of the heavenly bodies. With a brilliant leap of the imagination, he discussed not only the shape of the world (a drum), but also gave a remarkable explanation why the earth kept its place at the centre of a proportionate and harmonious universe (T23). In short, the world stays where it is because it has nowhere else to go.4 This is remarkable as an early preference for theory over the evidence of the senses, where the two conflict; for surely the senses would seem to confirm that nothing just hangs in place in mid-air.

T24 and T25 continue the story. Once hot and cold have emerged, hot (seen as fire) surrounds cold (seen as mist or vapour). The cold dries up under the action of heat and forms water and earth. The universe forms concentric rings, with fire on the outside, then mist, then water, which rests on earth. These are not stable elemental rings, but they interact through processes such as evaporation and precipitation. Anaximander’s stupendous picture of the finished universe has the earth surrounded by a number of fiery rings, each of which is enclosed and hidden by mist, as a tree is covered by bark, except for an aperture; that aperture—that glimpse into a vast fiery ring—is what we call the sun or the moon or a star. So the moon waxes and wanes as the mist surrounding its fiery ring is driven by a cosmic wind, generated by the sun, to block our view of it; the same goes for solar eclipses too.

Anaximander’s universe is symmetrical and harmonious, with the sun furthest from the earth, then the moon, and then presumably the fixed stars (on rings presumably nine times the size of the earth).5 Counter-intuitively, the brightness of the sun and the dimness of the stars is probably (unless he gleaned the idea from ancient Iran) what made Anaximander think that the sun was further away from the earth than the stars. Fire, as we have seen, being the lightest element, occupies the outer periphery; the sun is therefore closer to unadulterated fire than the stars are. Anaximander can account to a certain extent for the more regular motions of these heavenly bodies, but he seems to be unaware of the anomalous planets. His recognition that the sun is larger than it seems, and ascription of definite numbers to the distance of the sun and moon from the earth, is a recognition of the mathematics of perspective.

Whereas celestial and meteorological phenomena had in the past been the domain of the gods, Anaximander began (unless T10 is a reliable report about Thales) the Presocratic trend to explain these phenomena as the product of natural and comprehensible forces (e.g. T26). It was precisely this usurpation of the traditional functions of the gods that made this ‘modern’ thinking suspect to many people. And last, but not least, he seems to have had a vision of the universe as originally consisting of just elemental nature, before the birth of the human race. His description of the origins of humans and other animals is quite remarkable (T27–28), but does not allow us to go as far as to call him an evolutionist, a proto-Darwinian, because he seems to be describing no more than the first generation of creatures. It is to be noted how the gestation of the first human beings parallels that of the earth: both are enclosed within a casing before emerging. T28 looks as though it was an attempt to solve a chicken-and-egg problem: if human babies are not capable of looking after themselves at birth, how were the very first human beings born, and how did they manage to survive?

If Anaximander speculated about the origin of living things, it seems likely that he also had views about the origin of inanimate things, but there is a gap in our surviving evidence. After the four primary regions have taken up their proper places and formed the concentric layers of the universe, we do not know how other particular things were created. Perhaps it was something to do with the interplay of the primary opposites, hot and cold, and wet and dry. Anyway, although our evidence for Anaximenes is less overall than for Anaximander, this gap is securely filled. We have a good idea of how not only the whole universe, but also all the bits and pieces of it were formed in his theory.

We constantly read in our sources that air is the Aristotelian substrate of things, in Anaximenes’ opinion (e.g. T29). As usual, we need to take such an Aristotelian reading of the Presocratics with a pinch of salt, but in this case, with less salt than in the case of, say, Anaximander. For there can be little doubt that he dreamed up the twin processes of condensation and rarefaction as the means to explain how air became other things. Note, however, that this does not necessarily make air an Aristotelian substrate, rather than just an originative stuff. In Aristotelian theory the substrate, or underlying matter, persists through change. If Anaximenes were an Aristotelian, we would have to attribute to him the belief that this table in front of me is air in another form, greatly condensed. But it seems more likely that Anaximenes actually said that air when condensed turns into earth and so on, which is a different theory altogether. In fact, Anaximenes may have limited the number of things that air itself actually turns into, and left it up to this second order of substances to generate everything else (T29).

What drives Anaximenes’ theory seems to be the idea that the same laws that operate on the small scale, in the human body, also operate on the large scale, in the universe at large—that the universe is the macrocosm to the human’s microcosm (T30). We have already met this analogical argument in Anaximander’s parallel account of the gestation of the universe and the gestation of the first human beings. For Anaximenes, human beings are given life by air. In Greek terms, this is to say that human beings are animated or ensouled by air; since our soul holds us together (without it, our body perishes), then Anaximenes suggested that it does the same for the whole universe: it surrounds and interpenetrates the whole universe. The whole universe is mobile and alive. And surely another reason for Anaximenes’ choice of air as his originative stuff is that it is indistinct and adaptable.

Just as our breath can form clouds of mist and even droplets of moisture, so Anaximenes imagined that the primeval air or wind condensed first as cloud, and then as moisture (T29). This moisture then somehow condensed further into earth: did Anaximenes see silt thrown up from a river, or sand from the sea, and think that it was condensed water? Did he see that dust, tiny particles of solid matter, are left behind by raindrops? Did he see stalagmites and stalactites in a cave? At any rate, the whole cosmogonic process was, I think, suggested to Anaximenes by this simple analogy with human breath. Just as human breath is (apparently) colder when compressed and warmer when dilated (T31), so air at large can become something colder and more solid when condensed, and something warmer, even fiery, when rarefied. This is an important potential reference to primary and secondary qualities: the primary qualities of air are that it is more or less dense, but these qualities in turn lead it to have the secondary qualities of cold or heat. By implicitly creating a hierarchy like this, Anaximenes reduces the number of factors used to explain the fundamental features of the world, and so makes it more comprehensible. Moreover, if the reference to human breath goes back to Anaximenes, as seems likely, it is noteworthy as an early attempt, not quite to construct an experiment, but to argue by analogy from what can be known through the senses to what is inaccessible to the senses (see also T40).

It seems clear from T32 and T33 (and one or two other reports, not included here) that Anaximenes said something about the divine in relation to air. Unfortunately, all our reports are very late and unreliable. I find it very unlikely that Anaximenes went so far as to say that the gods emerged from the primeval air, the great god: this seems to confuse Anaximenes with later atomism.6 Cicero’s statement is perhaps closer to the truth, except for his mistake in saying that air was itself created. At any rate, perhaps we can conclude that Anaximenes attributed divinity to air, since it had taken over some of the creative and meteorological functions of the traditional gods, and since, like Anaximander’s apeiron, air is eternal. It is (as Cicero reports in T32, but we could have guessed anyway) always in motion, and so it imparts motion and change to everything else.7

The cosmogonic process continues (T34): moisture evaporates from the earth and, as it gets lighter, it becomes fiery and forms the heavenly bodies (T35). The sun may be a special case (T34): perhaps in its case immense winds condensed the evaporating moisture back into earth. There is no real contradiction between seeing the heavenly bodies as leaf-like and as fixed into the ice-like periphery (T37, T39). In any case, what Anaximenes may originally have said is that the fixed stars are fixed like nails in the periphery, while the sun and moon (and planets, if he recognized any) are floating like leaves. One of the images Anaximenes may well have been wanting to provoke by calling the periphery ‘ice-like’ is the image of leaves stuck on the surface of frozen water. Of course, the periphery is only ice-like: it cannot actually be ice, because on Anaximenes’ scheme of things it is hot out there at the periphery.

As well as explaining the original formation of the universe and its broad features, Anaximenes clearly went in some detail into celestial and meteorological phenomena (T36, T38, T40, T41). These testimonia bear witness to his views on earthquakes, thunder and lightning, nightfall, and the rainbow. In the latter case, at least, his opinion is accurate enough (given that ‘concentrated air’ presumably refers to mist or cloud), as far as it goes: we could not of course expect him to have knowledge of the refraction of light. Other late sources credit him with discoveries such as the true explanation of lunar eclipses, and the fact that the moon’s light is reflected sunlight. These are probably not to be trusted.


T1 (DK 11A5; KRS 64) The Lydians and the Medes even once fought a kind of night battle. In the sixth year, when neither side had a clear advantage over the other in the war, an engagement took place and it so happened that in the middle of the battle day suddenly became night. Thales of Miletus had predicted this loss of daylight to the Ionians by establishing in advance that it would happen within the limits of the year in which it did in fact happen. (Herodotus, Histories–2.6 Hude)

T2 (DK 11A4; KRS 65) This proposal by Bias of Priene was made to the Ionians after their defeat, but another good proposal had been put to them, even before the conquest of Ionia, by Thales of Miletus, a man originally of Phoenician lineage. He suggested that the Ionians should establish a single governmental council, that it should be in Teos (because Teos is centrally located in Ionia), and that all the other towns should be regarded effectively as outlying demes. (Herodotus, Histories 1.170.3 Hude)

T3 (DK 11A6; KRS 66) The story goes that Croesus did not know how his troops were going to cross the river, since the bridges I mentioned were not in existence at the time. But Thales was in the camp, and he helped Croesus by making the river flow on both sides of the army, instead of only to the left. This is how he did it, they say. He started upstream, above the army, and dug a deep channel which was curved in such a way that it would pass behind the army’s encampment; in this way he diverted the river from its original bed into the channel, and then, once he had got it past the army, he brought it back round to its original bed again. The immediate result of this division of the river was that it became fordable on both sides. (Herodotus, Histories 1.75.4–5 Hude)

T4 (DK 11A17; KRS 76) In his Astronomy Eudemus reports … that Thales was the first to discover the eclipse of the sun and the fact that the period of its solstices is not always equal. (Eudemus [fr. 94 in Dercyllidas ap. Theon of Smyrna, Mathematics Useful for Reading Plato 198.14–18 Hiller)

T5 (DK 11A3a; KRS 78)

Victory went to Thales,
Whose cleverness showed not least in the fact that

He is said to have measured the tiny stars of the Wain,

By which the Phoenicians sail.

(Callimachus, Iambus fr. 94.1–4 Pfeiffer)

T6 (DK 11A20; KRS 80) In his History of Geometry Eudemus attributes this theorem [the identity of triangles which have one side and two angles equal] to Thales, on the grounds that the method he is said to have used to demonstrate how far out to sea ships were must have made use of this theorem.* (Eudemus [fr. 87 Spengel] in Proclus, Commentary on Euclid 352.14–18 Friedlein)

T7 (DK 11A9; KRS 72) The story about Thales is a good illustration, Theodorus [illustrating the detachment of the philosopher from the humdrum reality of the world]: how he was looking upwards in the course of his astronomical investigations, and fell into a pothole, and a Thracian serving-girl with a nice sense of humour teased him for being concerned with knowing about what was up in the sky and not noticing what was right in front of him at his feet. (Plato, Theaetetus 174a4–8 Duke et al.)

T8 (DK 11A12; KRS 85) Most of the original seekers after knowledge recognized only first principles of the material kind as the first principles of all things. For that out of which all existing things are formed—from which they originally come into existence and into which they are finally destroyed—whose substance persists while changing its qualities, this, they say, is the element and first principle of all things … However, they disagree about how many of such first principles there are, and about what they are like. Thales, who was the founder of this kind of philosophy, says that water is the first principle (which is why he declared that the earth was on water); he perhaps reached this conclusion from seeing that everything’s food is moist, and that moisture is the source and prerequisite for the life of warmth itself (and the source of anything is the first principle of that thing). So, as I say, it was perhaps this that led him to reach this conclusion, and also the fact that the seeds of all things have a moist nature (and water is the first principle of the moist nature of moist things). And there are people who think that those in the dim, distant past who first began to reason about the gods, long before our present generation, shared this conception of the underlying nature; for these poets made Ocean and Tethys the parents of creation, and claimed that the gods took their oath upon water—the river Styx, as the poets call it.* (Aristotle, Metaphysics 983b6–32 Ross)

T9 (DK 11A14; KRS 84) Others say that the earth rests on water. This is the oldest account that has been passed down to us today, and they say it was the view of Thales of Miletus, that the earth stays where it is as a result of floating like a piece of wood or something similar (for none of these things is so constituted as to keep its position on air, but they do so on water)—as though the same argument did not apply to the water supporting the earth just as much as to the earth itself. After all, water is just as incapable of staying suspended in mid-air, and is also so constituted as to keep its position only when it is on something. (Aristotle, On the Heavens 294a28–294b1 Allan)

T10 (DK 11A15; KRS 88) Thales says that the world is held up by water and rides on it like a ship, and that what we call an earthquake happens when the earth rocks because of the movement of the water. (Seneca, Questions about Nature–4 Oltramare)

T11 (DK 11A22;KRS 89, 91) Thales too (as far as we can judge from people’s memoirs) apparently took the soul to be a principle of movement, if he said that the stone has soul because it moves iron … Some say that the universe is shot through with soul, which is perhaps why Thales too thought that all things were full of gods. (Aristotle, On the Soul 405a9–21, 411a7–9 Ross)


T12 (DK 12A1; KRS 94) Anaximander was the first to discover the gnomon and according to Favorinus in his Universal History he set one up on the Sundials in Lacedaemon, to indicate solstices and equinoxes. He also constructed a device to mark the passage of thehours.* (Diogenes Laertius, Lives of Eminent Philosophers 2.1.7–10 Long)

T13 (DK 12A6; KRS 98) Anaximander of Miletus, who studied under Thales, was the first who dared to draw the inhabited world on a tablet; subsequently Hecataeus of Miletus, a well-travelled man, improved the accuracy of this drawing and made it a thing of wonder.* … The ancients made the inhabited world round, with Greece in the centre and Delphi in the centre of Greece, since the navel of the earth is to be found there. (Agathemerus, Geography 1.1–2 Müller)

T14 (KRS 100) I am amazed when I see that not one of all the people who have drawn maps of the world has set it out sensibly. They show Ocean as a river flowing around the outside of the earth, which is as circular as if it had been drawn with a pair of compasses, and they make Asia and Europe the same size. (Herodotus, Histories–5 Hude)

T15 (DK 12A9, B1; KRS 101) Anaximander said that the first principle and element of existing things was the boundless; it was he who originally introduced this name for the first principle.* He says that it is not water or any of the other so-called elements, but something different from them, something boundless by nature, which is the source of all the heavens and the worlds in them. And he says that the original sources of existing things are also what existing things die back into ‘according to necessity; for they give justice and reparation to one another for their injustice in accordance with the ordinance of Time’, as he puts it, in these somewhat poetic terms. It is clear that, having noticed how the four elements change into one another, he decided not to make any of them the underlying thing, but something else beside them; and so he has creation take place not as a result of any of the elements undergoing qualitative change, but as a result of the opposites being separated off by means of motion, which is eternal. (Theophrastus [fr. 226a Fortenbaugh et al.] in Simplicius, Commentary on Aristotle’s ‘Physics’, CAG IX, 24.14–25 Diels)

T16 (KRS 102) Others—the natural scientists without exception—make something else (one of the things they identify as elements, such as water or air or something intermediate between them) the subject of which infinity is predicated.* (Aristotle, Physics203a16–18 Ross)

T17 (DK 12A16; KRS 103) The natural scientists fall into two schools of thought. Some make the underlying stuff single, and identify it either with one of the three [water, air, or fire], or with some other stuff which is more condensed than fire and more refined than air. Then they have condensation and rarefaction generate everything else, and so they arrive at a plurality of objects … Others, however, claim that the one contains oppositions, which are then separated out. This is the view of Anaximander and of those like Empedocles and Anaxagoras whose underlying stuff is simultaneously one and many. (Aristotle, Physics 187a 12–23 Ross)

T18 (KRS 106) There are five considerations which particularly lead people to infer that something infinite does exist … Third, there is the notion that the only possible explanation for the persistence of generation and destruction is that there is an infinite source from which anything which is generated is subtracted. (Aristotle, Physics 203b 15–20 Ross)

T19 (DK 12A16; KRS 105) However, there equally cannot be one simple infinite body, and this is so not only if, as some say, it is an extra body over and above the elements, which acts as the source of the elements, but also on a more straightforward view. Those who suggest that the infinite is not air or water, but this extra body, do so because they want to avoid everything else being destroyed by an infinite element. For the elements are related by mutual opposition (air is cold, for instance, while water is moist and fire is hot), and so if any one of them were infinite, the others would have been destroyed by now. So in fact, they say, there is this extra body which is the source of the elements. (Aristotle, Physics 204b22–9 Ross)

T20 (DK 12A15; KRS 108) Moreover, they take the infinite not to be subject to generation or destruction, on the grounds that it is a kind of principle, because anything generated must have a last part that is generated, and there is also a point at which the destruction of anything ends. That is why, as I say, the infinite is taken not to have an origin, but to be the origin of everything else—to contain everything and steer everything, as has been said by those thinkers who do not recognize any other causes (such as love or intelligence) apart from the infinite. They also call it the divine, on the grounds that it is immortal and imperishable; on this Anaximander and the majority of the natural scientists are in agreement. (Aristotle, Physics 203b7–15 Ross)

T21 (DK 12A27; KRS 132) They say that at first the whole region around the earth was wet, and that part of it began to dry up under the influence of the sun; this evaporating water causes winds and the turnings of the sun and moon, while the rest is the sea. And so they believe that the sea is still in the process of drying up and becoming less, and that eventually, some time in the future, it will all be dry. (Aristotle, On Celestial Phenomena 353b6–11 Bekker)

T22 (DK 12A10; KRS 121, 122) Anaximander says that the earth is cylindrical in shape, and three times as wide as it is deep. He says that, at the point when this universe was created, the part of the eternal which is productive of hot and cold was separated off, and that a kind of sphere of flame emerged from this and grew all around the vapour that surrounds the earth, like bark on a tree. The sun and the moon and the stars came into being, he says, when this fiery sphere broke off and became enclosed in certain circles. (Ps.-Plutarch, Miscellanies 2.5–11 Diels)

T23 (DK 12A26; KRS 123) There are some (including, among the thinkers of long ago, Anaximander) who say that the earth stays where it is because of equality. For something which is established in the centre and has equality in relation to the extremes has no more reason to move up than it does down or to the sides; it is impossible for it to move in opposite directions at the same time, and so it is bound to stay where it is. (Aristotle, On the Heavens 295b11–16 Allan)

T24 (DK 12A11; KRS 125, 129) He says that the stars are created as a circle of fire, which is separated off from the fire in the universe and surrounded by vapour. There are breathing-holes—pipe-like channels, as it were—where the stars appear; and so eclipses occur when the breathing-holes are blocked up. The moon appears to wax or wane at different times as a result of the blocking or opening of the channels. The circle of the sun is twenty-seven times the size of the earth, while the circle of the moon is eighteen times the size of the earth. The sun is the highest, and the circle of the fixed stars are the lowest … Winds occur when the finest vapours of the mist are separated off, gathered together, and set in motion. Rainfall is the result of the vapour which is sent up from the earth under the influence of the sun. Lightning occurs when wind breaks out and splits the clouds. (Hippolytus, Refutation of All Heresies 1.6.4–7 Marcovich)

T25 (DK 12A21; KRS 127) Anaximander says that the sun is equal in size to the earth, but that the circle from which it has its vent and by which it is carried around is twenty-seven times the size of that of the earth. (Aëtius, Opinions 2.21.1 Diels)

T26 (DK 12A23; KRS 130) Anaximander says that all these things [the phenomena of thunderstorms] are caused by wind: when wind has been enclosed within a dense cloud and compressed, and then breaks out as a result of its fineness and lightness, the rupture causes the noise, and the sundering, in contrast with the blackness of the cloud, causes the flash. (Aëtius, Opinions 3.3.1 Diels)

T27 (DK 12A30; KRS 133) Anaximander says that the first living creatures were born in a moist medium, surrounded by thorny barks, and that as they grew older they began to be fitted for a drier medium, until the bark broke off and they survived in a different form. (Aëtius, Opinions 5.19.4 Diels)

T28 (DK 12A30; KRS 135) Anaximander of Miletus imagined there arose from heated water and earth either fish or fish-like creatures, inside which human beings grew and were retained as fetuses up until puberty; then at last the creatures broke open, and men and women emerged who were already capable of feeding themselves. (Censorinus, On Birthdays 4.7.1–5 Jahn)


T29 (DK 13A5; KRS 140) Anaximenes of Miletus, the son of Eurystratus, was a companion of Anaximander, and shares his view that the underlying nature of things is single and infinite; however, unlike Anaximander, Anaximenes’ underlying nature is not boundless, but specific, since he says that it is air, and claims that it is thanks to rarefaction and condensation that it manifests in different forms in different things. When dilated, he says, it becomes fire, and when condensed it becomes first wind, then cloud, and then, as it becomes even denser, water, then earth, and then stones. Everything else comes from these things. He too makes motion eternal, and in his view motion is the cause of change as well. (Theophrastus [fr. 226a Fortenbaugh et al.] in Simplicius,Commentary on Aristotle’s ‘Physics’, CAG IX, 24.26–25.1 Diels)

T30 (DK 13B2; KRS 160) According to Anaximenes of Miletus,* the son of Eurystratus, air is the first principle of things, since it is the source of everything and everything is dissolved back into it. Just as in us, he says, soul, which is air, holds us together, so the whole universe is surrounded by wind and air (he uses ‘wind’ and ‘air’ as synonyms*). (Aëtius, Opinions–8 Diels)

T31 (DK 13B1; KRS 143) Anaximenes says that matter in a compressed and condensed state is cold, while in a dilated and ‘loose’ state (this is more or less exactly how he puts it) it is warm. And so, he says, when people say that man emits both warmth and cold from his mouth, they are not saying anything unreasonable. For breath gets cold when it is put under pressure and condensed by the lips, while when the mouth is relaxed the breath that escapes becomes warm as a result of its being in a rarefied state. (Plutarch,On the Primary Cold 947f8–948a3 Helmbold)

T32 (DK 13A10; KRS 144) Next came Anaximenes, who claimed that air was a god, which had been created, was infinitely huge, and was always in motion. (Cicero, On the Nature of the Gods 1.10.32–4 Plasberg)

T33 (DK 13A10; KRS 146) Anaximenes attributed all the causes of things to infinite air, but he did not deny the existence of gods or have nothing to say about them; however, he believed not that air was made by them, but that they emerged from air. (Augustine,The City of God 8.2.34–6 Dombart/Kalb)

T34 (DK 13A6; KRS 148) Anaximenes says that everything is created by the condensation, as it were, of air, or alternatively by its rarefaction, while motion exists eternally. He says that the first product of the felting* of the air is the earth, which is quite flat, which means that it can therefore ride on the air. The earth is the starting-point for the creation of the sun, moon, and all the other heavenly bodies. At any rate, he says that the sun is earth, but that it has become well and truly heated up as a result of the swiftness of its motion. (Ps.-Plutarch, Miscellanies 3.3–8 Diels)

T35 (DK 13A7; KRS 151, 156) According to Anaximenes, the earth is flat and rides on air, and similarly the sun, the moon and all the other heavenly bodies, which are made of fire, ride on the air because of their flatness. He says that the heavenly bodies have come into existence from the earth, as a result of the rising of moisture out of the earth. When this moisture is rarefied, it turns into fire, and the heavenly bodies are composed of this fire, which rises up into the heavens … He says that the heavenly bodies do not move under the earth, as others have supposed, but around the earth, as a strip of felt moves around one’s head; and that the sun is hidden not by being under the earth, but by being concealed by the higher parts of the earth and as a result of its increased distance from us … Rainbows are created when the sun’s rays fall on concentrated air. (Hippolytus, Refutation of All Heresies 1.7.4–8 Marcovich)

T36 (DK 13A14; KRS 157) Corroboration of the view that the regions of the earth to the north are highlands is found in the fact that many of the ancient speculators about celestial phenomena held that the sun does not pass under the earth but around it (specifically around this northern region), and disappears and causes night because the land is high in the north. (Aristotle, On Celestial Phenomena 354a27–32 Bekker)

T37 (DK 13A20; KRS 150) Anaximenes, Anaxagoras, and Democritus say that the flatness of the earth is responsible for its staying in place, because it does not cut the air beneath, but rests on it like a lid (as flat bodies obviously do) … According to these thinkers, thanks to its flatness the earth behaves in the same way in relation to the air beneath it, which does not have enough room to move, and so becomes compressed against the underside of the earth and remains motionless, like the water in a clepsydra.*(Aristotle, On the Heavens 294b 13–21 Allan)

T38 (DK 13A15; KRS 153) Anaximenes says that the turnings of the heavenly bodies are due to their being pushed off course by condensed air which repels them. (Aëtius, Opinions 2.23.1 Diels)

T39 (DK 13A14; KRS 154) Anaximenes says that the heavenly bodies are fixed like nails into the ice-like periphery; but some say that they are fiery leaves, like paintings. (Aëtius, Opinions 2.14.3 Diels)

T40 (DK 13A17; KRS 158) Anaximenes’ views coincide with those of Anaximander on these phenomena [see T21above], except that he adds what happens in the case of the sea, which gleams when it is cleaved by oars … Anaximenes says that clouds are caused by the increased thickening of the air, and that when air is concentrated even more rain is squeezed out; that hail happens when the water is frozen as it is falling, and snow when a windy ingredient is included in the moisture. (Aëtius, Opinions 3.3.2, 3.4.1 Diels)

T41 (DK 13A21; KRS 159) Anaximenes says that when the earth is soaked or dried out, it breaks up, and is shaken when peaks break off under these circumstances and fall down. And that, he says, is why earthquakes happen both during droughts and also during times of excessive rain. For during droughts, as I have said, the earth gets dry and breaks up, and when it becomes saturated by water it falls to pieces. (Aristotle, On Celestial Phenomena 365b6–12 Bekker)

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