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early C3rd CE. Anaximander is shown holding
a sundial. Image: Wikimedia Commons.
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The C3rd CE biographer Diogenes Laërtios (2.1–2; DK 12A1) states on the authority of the chronographer Apollodoros of Athens (C2nd BCE) that Anaximander was 64 years old in Olympiad 58.2 (547/6 BCE), which implies that he was born in 611/10 BCE, and goes on to say that he died shortly afterwards.1 The circumstances of his death are not known but, like the death of Thales, the date coincides with the capture of the Lydian capital Sardis by the Persians and their subsequent subjugation of the Ionian cities. However, Diogenes Laërtios then spoils things by saying that Anaximander was a contemporary of the Samian tyrant Polykrates, who did not come to power until some time in the 540s BCE. Clearly, this is anomalous, not only because of the mismatch of dates, but also because the link with Polykrates seems unmotivated and would normally be reserved for Pythagoras of Samos.
The doxographical tradition, which goes back to Theophrastos (C4th BCE), and neatly summarised in the Medieval Suda (s.v.)2, suggests that he was either related to Thales or in some way studied with him, but apart the name of his father, Praxiades and the connection to Thales, there is little further biographical information about him in the other ancient sources.3 One —no doubt apocryphal— story relates that upon being mocked by children for his habit of singing to himself, he resolved to try to sing better for them.1 It is not clear whether one should read this as the judgement of a beneficent father–figure or the sarcastic retort of a grumpy old man.
Despite the tendency of ancient writers to construct a narrative of ideas and to collect philosophers into schools of thought, it is not implausible that Anaximander might have known Thales if indeed he was a younger contemporary. Greek cities in the Archaic period, even large and prosperous ones like Miletos, were not very populous by modern standards and tended to be run as oligarchies or tyrannies. The number of prominent citizens (all relatively wealthy men) who were able to participate in civic life at any one time was probably no more that a couple of hundred at most.
Recently, the traditional dating of Anaximander (and his successor Anaximenes) has been challenged by Thibodeau (2019: 227–40).4 He argues that, owing to a mistake in identifying the sack of Sardis (it was sacked by the Persians in 546 BCE, and again by the Ionians in 499 BCE), the Olympiad dating (which may have been devised by Sosikrates of Rhodes) is wrong, and that we should believe Diogenes Laërtios when he synchronises Anaximander with Polykrates. Under this reformulation of the evidence, Anaximander's dates become c. 562 – c. 498 BCE, making him a younger contemporary of Pythagoras and Xenophanes. The argument is interesting but not, for me, persuasive. Since I want to focus on Anaximander's contribution to astronomy and science, I'll leave the discussion there.
Unlike Thales, it seems likely that Anaximander wrote at least one book on the cosmos, and he may have been the first to do so. The C4th CE philosopher Themistios says (Orations 26.317c, DK12A7):5
He is the first Greek that we know of who ventured to publish a written account of nature.Probably we should regard this as the first prose work, since earlier poetry written by, for example Hesiod, arguably also provided an 'account of nature'.
The Suda (s.v.)2 goes on to mention several books written by Anaximander with titles such as On Nature, Circuit of the Earth, On the Fixed Stars, and The Sphere. It is not clear how seriously we should take this elaboration. The title On Nature is a conventional title that was ascribed to many ancient scientists by later writers and seems plausible enough. The Circuit of the Earth may in fact refer to a map of the world perhaps with a simple gazetteer (see below). The book entitled On the Fixed Stars seems to indicate that he may have written a guide to the constellations and may have been the first person in Greece to present some kind of survey, but this is pure speculation. The one known as The Sphere is problematic. Anaximander is far too early to have written on the mathematics of the sphere, nor can it be regarded as referring to a globe of the Earth, since we know that he viewed the Earth's surface as flat. Possibly it should be taken either in the sense of the stellar sphere (which can be accommodated within his cosmology) and thus may have been another guide to the stars, or it may refer to the sphere of flame which was a part of his cosmogony and gave rise to the Sun, Moon and stars.
Evidence that Anaximander produced a map comes also from the C1st BCE geographer Strabo who says (1.1.11):6
That Homer began the study of geography has now been sufficiently demonstrated by my words. And the men who followed him are also well known as worthy of mention and true philosophers. The first two after Homer, as Eratosthenes says, were Anaximander, an acquaintance and fellow–citizen of Thales, and Hekataios the Milesian. Indeed, the former was the first to publish a geographical chart, and the latter left a work [on the subject], believed to be his from his other writings.We are given a little more information on this by the obscure C3rd CE geographer Agatheremos who is also following Eratosthenes (1.1, DK12A6):7
Anaximander the Milesian, a student of Thales, was the first to attempt to draw a map of the inhabited world. After him, Hekataios the Milesian, a much travelled man, improved on it so that it became an object of wonder.
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| The Babylonian map of the world (BM92687). Centred on the Euphrates river, it is highly schematic. |
As a native of the greatest seaport of the age Anaximander was in an unrivalled position to make such a map using the reports of Greek and perhaps Phoenician seafarers. However, it is likely to have been rather crude and simplistic, with Africa, Asia and Europe depicted as three roughly equal sectors of the world, a fact ridiculed in the next century by the historian Herodotos (4.36.2). It is likely, in reference to the map and other sources that Anaximander, like Thales, followed the ancient tradition of being a 'flat Earther'.
Not only do we have evidence of his books, we also have an alleged quotation which appears to be wrapped up inside a paraphrase originally due to Theophrastos (Simplicius Physics 24.13–25, DK 12A9, B1).8 This will be examined below.
Anaximander's contribution to physical theory and cosmogony was that he posited a primordial substance for all matter, as did most of the other early philosophers, but which differed from any of the traditional candidates such as air, earth, fire or water. The C6th CE philosopher and Aristotelian commentator Simplicius (On the Physics 24.13–25; DK12A9, B1) puts it thus:8
Anaximander . . . said that the principle and element of existing things was the 'undefined', being the first to introduce the name of this material. He says that it is neither water nor any other of the so called elements but consists of some other Apeiron ('Undefined') nature, from which come into being all the heavens and the worlds in them.From the supposed embedded quotation it would appear that Anaximander conceived of his fundamental substance apeiron as being capable of mutating into other substances, which in turn could revert back to this same substance.
And from which is the origin of everything and its destruction also, according to necessity
"for they give recompense to each other for injustice, according to the ordering of time",
expressing it in these rather poetic terms.
Unfortunately it is not clear whether the Greek word ἄπειρον which can mean variously 'boundless, indefinite, infinite' is to be conceived of in this context as being indefinite in extent or in some way indefinite in form or substance. Since our main concern is with his astronomy rather than his physics, we'll leave the matter there.
In terms of practical astronomy, we are told by the C2nd/3rd CE chronicler and theologian Eusebius that Anaximander introduced the sundial into Greece (Preparation for the Gospel 10.14.11; DK12A4), both for the purposes of telling the time and marking solstices and equinoxes. The gnomon and sundial, according to Herodotos (2.109.3)9 were Babylonian inventions. That Anaximander should have taken an interest in this is certainly plausible although the mechanism of transmission is not clear.
The international politics of the late C7th and the early C6th cannot have made such cultural and technical borrowing from Mesopotamia straightforward. However, the Greeks had trading posts in the Levant at this time, such as Al–Mina and Tell Sukas; and following the overthrow of the Assyrian Empire in 609 BCE by the Babylonians and their allies, cultural flow may have restarted after a brief hiatus. Alternatively, the usefulness of the gnomon may have been learned from Phoenician traders visiting Greek cities like Miletos. In a somewhat garbled passage Diogenes Laërtios states that Anaximander set up a gnomon and sundial in Sparta and used it to mark the solstices and equinoxes.1 This, of course, is possible, although Sparta seems an unusual location.
For his main contribution to astronomy Anaximander offered a complete physical model of the cosmos and was probably the first person to do so. Aristotle sets the scene (On the Heavens 295b10–16, DK12A26):10
But some say that it [the Earth] remains in place because of its uniformity, as does Anaximander of the old school. For that which is situated in the middle and equally spaced in relation to the edges has no propensity to be carried up or down or sideways; and it is impossible for it to move in opposite ways at the same time, so it remains still by necessity.Aristotle does not accept this argument but describes it as ingenious (κομψῶς). In fact, it is an argument from symmetry and marks quite a breakthrough of understanding on Anaximander's part. No longer does the Earth need rest on anything. It is perfectly possibly for it to remain free floating in the middle of space since there is effectively no up or down as there is on Earth. Anaximander has for the first time removed himself from an Earthly viewpoint and seen the Earth as a part, the central part, of the cosmos.
A succinct description of Anaximander's cosmology is given by the C1st/C2nd BCE theologian, Hippolytos of Rome, in his book The Refutation of All Heresies (1.6.3–5):11
[3] The earth is suspended, supported by nothing, remaining in place on account of its equal distance from all things. Its shape is curved, circular, similar to a stone column drum. We tread upon one of the surfaces, the other is opposite. [4] The heavenly bodies are a circle of fire, separated from the cosmic fire and surrounded by air. There are certain pores in tubes for exhalations through which the heavenly bodies shine. When these exhalations are obstructed eclipses take place. [5] The Moon appears sometimes full and sometimes waning, according to the obstruction or opening of its pores. The circle of the Sun is twenty–seven times larger than <that of the Earth; the Moon, eighteen times larger. The sun is situated in the highest part, and the circles of the fixed stars in the lowest.This description is supported by several passages in the C1st/C2nd CE philosopher Aëtios (P2.20.1, S 1.25.1C; DK12A21):
Anaximander [says the Sun] is a circle twenty–times the size of the Earth, similar to a cartwheel with a hollow rim, full of fire, one part emitting the fire through an opening as jet. And this is the Sun.(P21.1):
Anaximander [says] the Sun is equal to the Earth, and the circle on which it has its hole and on which it revolves is twenty–seven times the size of the Earth.(P24.2):
Anaximander [says an eclipse of the Sun occurs] when the mouth of the fire hole is closed off.(P2.25.1, S2.26.1a; DK12A22):
Anaximander [says the Moon] is a circle nineteen times the size of the Earth, like a cartwheel with a hollow rim, full of fire, like that of the Sun, lying aslant, as does the Sun, having a single vent like a jet of fire. And eclipses occur with the turnings of the wheel.(P 2.28.1, S1.26.2):
Anaximander [says] it [the Moon] has its own light, but somehow it is gentler.(P2.29.1, S2.26.3):
Anaximander [says an eclipse of the Moon occurs] when the opening on the wheel is blocked.(P2.16.5, S1.24.2c; DK12A18):
Anaximander [says the stars] are borne by circles and spheres upon which each one travels.Putting all this together we get the following model. The Earth is a short cylinder, with its height equal to one third of its diameter (Pseudo– Plutarch Miscellany 2). It resembles the drum of an ancient Greek column and we live on just one of the flat surfaces. It stays in the centre of the Cosmos because it is in equilibrium and equidistant from all other celestial bodies. So far, this is not too dissimilar to the inherited view, except for the freely floating Earth which does not rest on anything.
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The cosmos according to Anaximander showing the relative
sizes of the Earth, the sphere of the stars. and the rings
of the Sun and Moon. Image: Wikimedia Commons.
|
Following on from his conception of the undefined primordial substance and its modification in parts by operations of condensation and rarefaction, Anaximander suggests that celestial objects are rings of fire (arising by rarefaction) which are enclosed by tubes of mist or smoke (arising by condensation), likening these structures to the rims of cartwheels.
The object that we think we see is in fact a hole or opening in the tube which reveals the fire inside. The phases of the Moon, for example, occur because the hole is in different states of being closed off: at full Moon, the hole is wide open; at new Moon, the hole is fully closed. Solar eclipses are explained similarly with (presumably) a more rapid opening and closing of the aperture, and the internal fire is much brighter than that of the Moon. In the case of the Sun and Moon the diameter of each tube is equal to the diameter of the Earth.
The rings of the Sun and Moon (and presumably the planets, but Anaximander does not mention these in the sources) are inclined to the plane of the Earth's inhabited surface. This is so arranged in order to explain the path of what we would now term the celestial equator. The rings of the stars, however, are parallel to the celestial equator and are presumably arranged with decreasing radii so as to form a sphere. The diameter of the circle of the Sun is 27 to 28 times that of the Earth, the diameter of the Moon’s circle 18 to 19 times and that of the planets and stars 9 to 10 times (most stellar rings are smaller but lie above or below the plane of the Earth).
The notion of the ecliptic, the central line of the zodiac, and the path of the Sun and approximately the Moon (and also the planets, though Anaximander does not mention these) relative to the paths of the fixed stars, is not explicitly acknowledged. Anaximander probably knew about the zodiac (it was a recently completed development in Babylonian astronomy) and must have realised that the Sun and Moon do not move along paths parallel to the stars, but evidence for how he dealt with it within his scheme is wanting. However, it is not difficult to see how the ecliptic could have been simulated in his cosmology by having the rings move slowly up and down along their axes relative to the Earth over the course of the year.12
As a physical theory of the cosmos, of course, this is all rather bizarre even by the standards of later ancient Greek cosmology. And, we do not know how Anaximander defended it against any shortcomings that may have been pointed out to him. However, in a sense, his vision of the cosmos was a breakthrough. People had long observed that certain stars (circumpolar stars) travel around in circles —indeed Homer tells us as much. Anaximander generalised this and pointed out that all the other celestial bodies must also travel in circles, even if we could not directly observe them doing so. Since the Earth was in the middle of the cosmos some celestial bodies must pass under the Earth and not around its rim as in earlier conceptions.
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| An intepretation of Anaximander's cosmos at different times of the year. The earth is a tiny squat cylinder in the centre inclined to the plane of the rings. The stars and planets revolve on individual rings configured to form a sphere. The Sun and Moon rings can move along their axis of rotation. The radial lines represent light escaping from the rings. Visualisation by Dirk L. Couprie. Image: Wikimedia Commons. |
As we have seen, his model could accommodate the varying declinations of the Sun and Moon over the course of the year by having their rings move up and down along their axes. By contrast, the daily variations in height are caused by the cylinder of the Earth itself being inclined with respect to the plane of the rings (though Anaximander would probably have thought of the relationship as the other way round). We don't know what led him to the conjecture of the rings, but perhaps he felt that the cosmos required a physical framework in order to prevent celestial objects from falling to Earth.
There was another innovation in Anaximander's model too, namely that the cosmos had depth. In the traditional view, all celestial bodies lay at more or less the same distance from Earth, whereas Anaximander took specific steps to point out the contrary. He placed the stars nearer to the Earth than the Moon or Sun, and at first sight this seems to fall foul of the objection that we sometimes see stars occulted by the Moon. However, as Couprie points out,13 we don't usually see that in reality. What we typically see is the star disappearing and then reappearing as it approaches the bright Moon, just as we would an artificial satellite. It is the glare of the Moon, Anaximander may have argued (although there is no proof of this), that seems to make the star disappear. Only by noticing a star, or more probably a planet (again, as far as we know, Anaximander did not distinguish the two), disappearing behind the unilluminated part of the Moon when the latter is in crescent phase could we conclude that the Moon was moving in front of the star. This effect is obvious in binoculars or a telescope, but much harder to observe with the naked eye. The argument from occultation, therefore, is not as strong as it might first appear.
The reason that Anaximander placed the stars nearer to the Earth than the Sun or Moon may have been that he was aware of their geographical variation in altitude. That is, he knew, as many mariners must have known, that as one travels further south in the northern hemisphere familiar stars appear higher in the sky, and lower in sky if one travels north. This, of course, is actually caused by the curvature of the Earth and the observer's change in latitude. But if you believe in a flat Earth as Anaximander did, then the stars need to be quite nearby for the effect to happen.
Of course, Anaximander did not know the distances between places with any degree of accuracy and he could not have done any such calculation, but had he been able to do so in the Sirius example, he could have derived the distances of the Moon and the Sun as 4662 and 6993 kilometres respectively, according to his 9–18–27 ratio. Unfortunately, this would also make the Earth disk excessively small at only 259 kilometres in diameter, thus showing an immediate contradiction.
However, by playing around with rough diagrams of triangles he would have realised that a flat Earth necessitated that the stars must be quite close relative to the size of the Earth. Generally speaking, the height of the stars would have to be of a similar order of magnitude to the distances encountered on Earth. And it may have been this realisation that prompted him to put the stars closer to the Earth than the Sun and Moon.
As for the ratios that he chose for the distances of the Stars, Moon and Sun, this seems quite arbitrary, but as Couprie points out,13 it is quite possible that Anaximander chose a factor of nine in his cosmic model because he was reminded of Hesiod's description (Theogony 720–5) of an anvil falling to Earth from Heaven, and taking nine days to do. Nine had thus become a kind of canonical number, representing a huge distance, but one that related the Earth to the rest of the universe.
In summary, Anaximander's model of the cosmos is somewhat arbitrary and speculative, and certainly not informed by quantitative observation. Moreover, it is highly likely that, given the fragmentary nature of the sources, our understanding of it is not only incomplete but may actually be in part mistaken. However, it does appear the Anaximander attempted to grapple with at least some of the observed phenomena concerning the sky and the Earth's relationship to it. His theory rested on the false inherited assumption of a flat, immobile Earth and a false novel assumption about the celestial bodies, and as a consequence came to a false conclusion, but its process of construction may have been quite reasonable.
We don't know to what extent Anaximander's model of the cosmos gained currency. Presumably, it won a degree of favour by some of his successors otherwise we would not know about it at all. Probably, it was also known to, but not necessarily accepted by, later philosophers like Anaxagoras and Demokritos who also believed in a flat Earth. However, once it was realised that the Earth is spherical as well as the rest of the cosmos, which happened in the late C5th BCE, its rationale must have fallen away quite rapidly.
Lunar crater: Anaximander (diameter 69 km).
NOTES
1. (Diogenes Laërtios: 2.1–2; DK 12A1) [1] Ἀναξίμανδρος Πραξιάδου Μιλήσιος. οὗτος ἔφασκεν ἀρχὴν καὶ στοιχεῖον τὸ ἄπειρον, οὐ διορίζων ἀέρα ἢ ὕδωρ ἢ ἄλλο τι. καὶ τὰ μὲν μέρη μεταβάλλειν, τὸ δὲ πᾶν ἀμετάβλητον εἶναι. μέσην τε τὴν γῆν κεῖσθαι, κέντρου τάξιν ἐπέχουσαν οὖσαν σφαιροειδῆ: τήν τε σελήνην ψευδοφαῆ, καὶ ἀπὸ ἡλίου φωτίζεσθαι, ἀλλὰ καὶ τὸν ἥλιον οὐκ ἐλάττονα τῆς γῆς, καὶ καθαρώτατον πῦρ. Εὗρεν δὲ καὶ γνώμονα πρῶτος καὶ ἔστησεν ἐπὶ τῶν σκιοθήρων ἐν Λακεδαίμονι, καθά φησι Φαβωρῖνος ἐν Παντοδαπῇ ἱστορίᾳ, τροπάς τε καὶ ἰσημερίας σημαίνοντα, καὶ ὡροσκοπεῖα κατεσκεύασε.
[2] καὶ γῆς καὶ θαλάσσης περίμετρον πρῶτος ἔγραψεν, ἀλλὰ καὶ σφαῖραν κατεσκεύασε. Τῶν δὲ ἀρεσκόντων αὐτῷ πεποίηται κεφαλαιώδη τὴν ἔκθεσιν, ᾗ που περιέτυχεν καὶ Ἀπολλόδωρος ὁ Ἀθηναῖος: ὃς καί φησιν αὐτὸν ἐν τοῖς Χρονικοῖς τῷ δευτέρῳ ἔτει τῆς πεντηκοστῆς ὀγδόης Ὀλυμπιάδος ἐτῶν εἶναι ἑξήκοντα τεττάρων καὶ μετ᾽ ὀλίγον τελευτῆσαι, ἀκμάσαντά πη μάλιστα κατὰ Πολυκράτην τὸν Σάμου τύραννον. τούτου φασὶν ᾄδοντος καταγελάσαι τὰ παιδάρια, τὸν δὲ μαθόντα φάναι, "βέλτιον οὖν ἡμῖν ᾀστέον διὰ τὰ παιδάρια." Γέγονε δὲ καὶ ἄλλος Ἀναξίμανδρος ἱστορικός, καὶ αὐτὸς Μιλήσιος τῇ Ἰάδι γεγραφώς.
[1] Anaximander, the son of Praxiades, was a native of Miletos. He laid down as his first principle and element that which is unlimited without defining it as air or water or anything else. He held that the parts undergo change, but the whole is unchangeable; that the Earth is in the middle, spherical and occupying the centre; that the Moon, shining falsely, gets its light from the Sun, and also that the Sun is no smaller than the Earth and consists of the purest fire. He first discovered the gnomon and set it up as a sundial in Sparta, as Favorinus says in his 'Universal History', to mark the solstices and the equinoxes, and he also constructed clocks.
[2] He was the first to draw the outline of land and sea, and he constructed a globe as well. He made a summary exposition of his doctrines which Apollodoros of Athens happened to possess. He says in his 'Chronicle' that in the second year of the 58th Olympiad Anaximander was sixty-four, and that he died shortly afterwards, flourishing roughly at the same time as Polykrates, the king of Samos. They say that once some children laughed at his singing and that, when he heard of it, he said, "Then I must sing better for the children." There is another Anaximander, also of Miletos, a historian who wrote in the Ionic dialect.
2. (Suda s.v.) Ἀναξίμανδρος, Πραξιάδου, Μιλήσιος, φιλόσοφος, συγγενὴς καὶ μαθητὴς καὶ διάδοχος Θάλητος. πρῶτος δὲ ἰσημερίαν εὗρε καὶ τροπὰς καὶ ὡρολογεῖα καὶ τὴν γῆν ἐν μεσαιτάτῳ κεῖσθαι. γνώμονά τε εἰσήγαγε καὶ ὅλως γεωμετρίας ὑποτύπωσιν ἔδειξεν. ἔγραψε Περὶ φύσεως, Γῆς περίοδον, καὶ Περὶ τῶν ἀπλανῶν καὶ Σφαῖραν καὶ ἄλλα τινά.
Son of Praxiades, Milesian, philosopher, a relative, student and successor of Thales. He was the first to determine the equinox and solstices and to devise clocks, and said that the earth is situated right in the middle [of the cosmos]. He also introduced the gnomon and generally explained the basis of geometry. He wrote 'On Nature', 'Circuit of the Earth', and 'On the Fixed Stars' and 'The Globe' amongst other works.
3. Amongst them, Strabo 1.1.11, Simplicius On the Physics 24.13 (DK 12A9), Hippolytos Refutation of All Heresies 1.6.1–2 (DK 12A11), Pseudo–Plutarch Miscellany 2 (DK12A10), Eusebius Preparation for the Gospel 10.14.11 (DK12A4), Suda s.v.
4. Thibodeau, Philip (2019). The Chronology of the Early Greek Philosophers. Connecticut.
5. (Themistios Orations 26.317c, DK12A7) Ἐθάρρησε πρῶτος ὧν ἴσμεν Ἑλλήνων λόγον ἐξενεγκεῖν περὶ φύσεως ξυγγεγραμμένον.
6. (Strabo 1.1.11) νυνὶ δὲ ὅτι μὲν Ὅμηρος τῆς γεωγραφίας ἦρξεν, ἀρκείτω τὰ λεχθέντα. φανεροὶ δὲ καὶ οἱ ἐπακολουθήσαντες αὐτῷ ἄνδρες ἀξιόλογοι καὶ οἰκεῖοι φιλοσοφίας, ὧν τοὺς πρώτους μεθ᾽ Ὅμηρον δύο φησὶν Ἐρατοσθένης, Ἀναξίμανδρόν τε Θαλοῦ γεγονότα γνώριμον καὶ πολίτην καὶ Ἑκαταῖον τὸν Μιλήσιον: τὸν μὲν οὖν ἐκδοῦναι πρῶτον γεωγραφικὸν πίνακα, τὸν δὲ Ἑκαταῖον καταλιπεῖν γράμμα, πιστούμενον ἐκείνου εἶναι ἐκ τῆς ἄλλης αὐτοῦ γραφῆς.
7. (Agathemeros 1.1, DK12A6).
8. (Simplicius On the Physics 24.13).
9. (Herodotos: 2.109.3) δοκέει δέ μοι ἐνθεῦτεν γεωμετρίη εὑρεθεῖσα ἐς τὴν Ἑλλάδα ἐπανελθεῖν: πόλον μὲν γὰρ καὶ γνώμονα καὶ τὰ δυώδεκα μέρεα τῆς ἡμέρης παρὰ Βαβυλωνίων ἔμαθον οἱ Ἕλληνες.
It seems to me that from this [sc. activities in Egypt] knowledge of geometry came into Greece. The sundial with its gnomon, and the twelve divisions of the day, the Greeks learned from the Babylonians.
10 (Aristotle On the Heavens 295b11–16).
11. Hippolytos Refutation of All Heresies 1.6.3–7.
12. The C1st CE Roman writer Pliny the Elder (Natural History 2.31, DK12A5) asserts that Anaximander discovered the obliquity of the ecliptic but such a notion this seems not to fit in with his cosmology. More likely, this should be attributed to Anaxagoras a century later.
13. Couprie, Dirk L. 'Anaximander', Internet Encyclopedia of Philosophy (https://www.iep.utm.edu/anaximan/ retrieved 27/05/2020).
Last updated 18/07/20
