Miletus (/ˈθeɪliːz/; Greek: Θαλῆς (ὁ
Μῑλήσιος), Thalēs; c. 624 – c. 546 BC) was a
pre-Socratic Greek philosopher, mathematician, and astronomer from
Asia Minor (present-day
Milet in Turkey). He was one of the
Seven Sages of Greece. Many, most notably Aristotle, regarded him as
the first philosopher in the Greek tradition, and he is
otherwise historically recognized as the first individual in Western
civilization known to have entertained and engaged in scientific
Thales is recognized for breaking from the use of mythology to explain
the world and the universe, and instead explaining natural objects and
phenomena by theories and hypotheses, i.e. science. Almost all the
Pre-Socratic philosophers followed him in explaining nature as
deriving from a unity of everything based on the existence of a single
ultimate substance, instead of using mythological explanations.
Aristotle reported Thales' hypothesis that the originating principle
of nature and the nature of matter was a single material substance:
Thales used geometry to calculate the heights of
pyramids and the distance of ships from the shore. He is the first
known individual to use deductive reasoning applied to geometry, by
deriving four corollaries to Thales' theorem. He is the first known
individual to whom a mathematical discovery has been attributed.
2.2 Thales' theorems
2.3 Cosmology: water as a first principle
2.4 Beliefs in divinity
5.2 Rise of theoretical inquiry
6 Influence on others
7 Reliability of sources
8 See also
11 Further reading
12 External links
See also: Seven Sages of Greece
Thales was probably born in the city of
Miletus around the mid-620s
BC. The ancient writer Apollodorus of Athens writing during the 2nd
century BC, thought
Thales was born about the year 625 BC.
Herodotus, writing in the fifth century BC, described
Thales as "a
Phoenician by remote descent". The later historian Diogenes
Laertius, in his Lives of the Philosophers, references Herodotus,
Duris, and Democritus, who all agree "that
Thales was the son of
Examyas and Cleobulina, and belonged to the Thelidae who are
Phoenicians." He then states that "Most writers, however, represent
him as a native of
Miletus and of a distinguished family."
The dates of Thales' life are not exactly known, but are roughly
established by a few datable events mentioned in the sources.
Herodotus (and as determined by modern methods) Thales
predicted the solar eclipse of May 28, 585 BC. Diogenes
Laërtius quotes the chronicle of
Apollodorus of Athens as saying that
Thales died at the age of 78 during the 58th Olympiad
(548–545 BC) and attributes his death to heat stroke while
watching the games.
Diogenes Laërtius states that "according to
Herodotus and Douris and
Democritus", Thales' parents were Examyes and Cleobuline, whose names
are indigenous Carian and Greek, respectively.
delivers conflicting reports: one that
Thales married and either
fathered a son (Cybisthus or Cybisthon) or adopted his nephew of the
same name; the second that he never married, telling his mother as a
young man that it was too early to marry, and as an older man that it
was too late.
Plutarch had earlier told this version:
Thales and asked him why he remained single;
Thales answered that he
did not like the idea of having to worry about children. Nevertheless,
several years later, anxious for family, he adopted his nephew
Thales involved himself in many activities, taking the role of an
innovator. Some say that he left no writings, others say that he wrote
Solstice and On the Equinox. (No writing attributed to him has
Diogenes Laërtius quotes two letters from Thales: one to
Pherecydes of Syros, offering to review his book on religion, and one
to Solon, offering to keep him company on his sojourn
from[clarification needed] Athens.
Thales identifies the Milesians as
Thales' principal occupation was engineering.
He was aware of the existence of the lodestone, and was the first to
be connected to knowledge of this in history. According to Aristotle,
Thales thought lodestones had souls, because iron is attracted to them
(by the force of magnetism). According to Hieronymus, historically
Thales found the height of pyramids by
comparison between the lengths of the shadows cast by a person and by
An olive mill and an olive press dating from Roman times in Capernaum,
Several anecdotes suggest
Thales was not just a philosopher, but also
A story, with different versions, recounts how
Thales achieved riches
from an olive harvest by prediction of the weather.
In one version, he bought all the olive presses in
predicting the weather and a good harvest for a particular year.
Another version of the story has
Aristotle explain that
reserved presses in advance, at a discount, and could rent them out at
a high price when demand peaked, following his prediction of a
particularly good harvest.
Aristotle explains that Thales' objective
in doing this was not to enrich himself but to prove to his fellow
Milesians that philosophy could be useful, contrary to what they
thought, or alternatively,
Thales had made his foray into
enterprise because of a personal challenge put to him by an individual
who had asked why, if
Thales was an intelligent famous philosopher, he
had yet to attain wealth. This first version of the story would
constitute the first historically known creation and use of futures,
whereas the second version would be the first historically known of
creation and use of options.
Thales’ political life had mainly to do with the involvement of the
Ionians in the defense of
Anatolia against the growing power of the
Persians, who were then new to the region. In neighbouring Lydia, a
king had come to power: Croesus, who was somewhat too aggressive for
the size of his army. He had conquered most of the states of coastal
Anatolia, including the cities of the Ionians. The story is told in
The Lydians were at war with the Medes, who were a remnant of the
first wave of migration of ancient Iranian peoples, who had
subsequently settled into the region, over the issue of refuge the
Lydians had given to some
Scythian soldiers of fortune inimical to the
Medes. The war endured for five years, but in the sixth an eclipse of
Sun (mentioned above) spontaneously halted a battle in progress
(the Battle of Halys).
It seems that
Thales had predicted this solar eclipse. The Seven Sages
were most likely already in existence, as
Croesus was also heavily
Solon of Athens, another sage. Whether
present at the battle is not known, nor are the exact terms of the
prediction, but based on it the Lydians and
Medes made peace
immediately, swearing a blood oath.
Medes were dependencies of the Persians under Cyrus.
sided with the
Medes against the Persians and marched in the direction
of Iran (with far fewer men than he needed). He was stopped by the
river Halys, then unbridged. This time he had
Thales with him, perhaps
by invitation. Whatever his status, the king gave the problem to him,
and he got the army across by digging a diversion upstream so as to
reduce the flow, making it possible to ford the river. The channels
ran around both sides of the camp.
The two armies engaged at Pteria in Cappadocia. As the battle was
indecisive but paralyzing to both sides,
Croesus marched home,
dismissed his mercenaries and sent emissaries to his dependents and
allies to ask them to dispatch fresh troops to Sardis. The issue
became more pressing when the Persian army showed up at Sardis.
Diogenes Laërtius tells us that
Thales gained fame as a counselor
when he advised the Milesians not to engage in a symmachia, a
"fighting together", with the Lydians. This has sometimes been
interpreted as an alliance, but a ruler does not ally with his
Croesus was defeated before the city of
Sardis by Cyrus, who
Miletus because it had taken no action. Cyrus was
so impressed by Croesus’ wisdom and his connection with the sages
that he spared him and took his advice on various matters.
Ionians were now free.
Herodotus says that
Thales advised them to
form an Ionian state; that is, a bouleuterion ("deliberative body") to
be located at
Teos in the center of Ionia. The Ionian cities should be
demoi, or "districts". Miletus, however, received favorable terms from
Cyrus. The others remained in an Ionian League of 12 cities (excluding
Miletus now), and were subjugated by the Persians.
Herodotus reported that most of his fellow Greeks believe that
Thales did divert the river Halys to assist King Croesus' military
endeavors, he himself finds it doubtful.
The Ionic Stoa on the Sacred Way in Miletus
Diogenes Laërtius tells us that the Seven Sages were created in
the archonship of Damasius at
Athens about 582 BC and that Thales
was the first sage. The same story, however, asserts that Thales
emigrated to Miletus. There is also a report that he did not become a
student of nature until after his political career. Much as we would
like to have a date on the seven sages, we must reject these stories
and the tempting date if we are to believe that
Thales was a native of
Miletus, predicted the eclipse, and was with
Croesus in the campaign
Thales received instruction from an Egyptian priest. It was fairly
certain that he came from a wealthy, established family, in a class
which customarily provided higher education for their children.
Moreover, the ordinary citizen, unless he was a seafaring man or a
merchant, could not afford the grand tour in Egypt, and did not
consort with noble lawmakers such as Solon.
Total eclipse of the Sun
Lives of Eminent Philosophers
Lives of Eminent Philosophers Chapter 1.39,
Laërtius relates the several stories of an expensive object that is
to go to the most wise. In one version (that Laërtius credits to
Callimachus in his Iambics) Bathycles of Arcadia states in his will
that an expensive bowl "'should be given to him who had done most good
by his wisdom.' So it was given to Thales, went the round of all the
sages, and came back to
Thales again. And he sent it to Apollo at
Didyma, with this dedication...'
Thales the Milesian, son of Examyas
[dedicates this] to Delphinian Apollo after twice winning the prize
from all the Greeks.'"
See also: The Astrologer who Fell into a Well
Thales predicted the solar eclipse of May 28, 585 BC. Thales
also described the position of Ursa Minor, and thought the
constellation might be useful as a guide for navigation at sea. He
calculated the duration of the year and the timings of the equinoxes
and solstices. He is additionally attributed with the first
observation of the Hyades and with calculating the position of the
Plutarch indicates that in his day (c. AD 100) there was
an extant work, the Astronomy, composed in verse and attributed to
Early Greeks, and other civilizations before them, often invoked
idiosyncratic explanations of natural phenomena with reference to the
will of anthropomorphic gods and heroes. Instead,
Thales aimed to
explain natural phenomena via rational hypotheses that referenced
natural processes themselves. For example, rather than assuming that
earthquakes were the result of supernatural whims
them by hypothesizing that the
Earth floats on water and that
earthquakes occur when the
Earth is rocked by waves.
Thales was a hylozoist (one who thinks that matter is alive, i.e.
Aristotle wrote (
De Anima 411 a7-8) of Thales:
Thales thought all things are full of gods.
Aristotle posits the
Thales thought on matter generally containing souls, to
Thales thinking initially on the fact of, because magnets move iron,
the presence of movement of matter indicated this matter contained
Thales, according to Aristotle, asked what was the nature (Greek
arche) of the object so that it would behave in its characteristic
Physis (φύσις) comes from phyein (φύειν), "to grow",
related to our word "be". (G)natura is the way a thing is
"born", again with the stamp of what it is in itself.
Aristotle characterizes most of the philosophers "at first"
(πρῶτον) as thinking that the "principles in the form of matter
were the only principles of all things", where "principle" is arche,
"matter" is hyle ("wood" or "matter", "material") and "form" is eidos.
Arche is translated as "principle", but the two words do not have
precisely the same meaning. A principle of something is merely prior
(related to pro-) to it either chronologically or logically. An arche
(from ἄρχειν, "to rule") dominates an object in some way. If
the arche is taken to be an origin, then specific causality is
implied; that is, B is supposed to be characteristically B just
because it comes from A, which dominates it.
The archai that
Aristotle had in mind in his well-known passage on the
first Greek scientists are not necessarily chronologically prior to
their objects, but are constituents of it. For example, in pluralism
objects are composed of earth, air, fire and water, but those elements
do not disappear with the production of the object. They remain as
archai within it, as do the atoms of the atomists.
Aristotle is really saying is that the first philosophers were
trying to define the substance(s) of which all material objects are
composed. As a matter of fact, that is exactly what modern scientists
are attempting to accomplish in nuclear physics, which is a second
Thales is described as the first western
Thales was known for his innovative use of geometry. His understanding
was theoretical as well as practical. For example, he said:
Megiston topos: hapanta gar chorei (Μέγιστον τόπος·
ἄπαντα γὰρ χωρεῖ.)
The greatest is space, for it holds all things.
Topos is in Newtonian-style space, since the verb, chorei, has the
connotation of yielding before things, or spreading out to make room
for them, which is extension. Within this extension, things have a
position. Points, lines, planes and solids related by distances and
angles follow from this presumption.
Thales understood similar triangles and right triangles, and what is
more, used that knowledge in practical ways. The story is told in DL
(loc. cit.) that he measured the height of the pyramids by their
shadows at the moment when his own shadow was equal to his height. A
right triangle with two equal legs is a 45-degree right triangle, all
of which are similar. The length of the pyramid's shadow measured from
the center of the pyramid at that moment must have been equal to its
This story indicates that he was familiar with the Egyptian seked, or
seqed, the ratio of the run to the rise of a slope (cotangent). The
seked is at the base of problems 56, 57, 58, 59 and 60 of the Rhind
papyrus — an ancient Egyptian mathematical document.
In present-day trigonometry, cotangents require the same units for run
and rise (base and perpendicular), but the papyrus uses cubits for
rise and palms for run, resulting in different (but still
characteristic) numbers. Since there were 7 palms in a cubit, the
seked was 7 times the cotangent.
To use an example often quoted in modern reference works, suppose the
base of a pyramid is 140 cubits and the angle of rise 5.25 seked.
The Egyptians expressed their fractions as the sum of fractions, but
the decimals are sufficient for the example. What is the rise in
cubits? The run is 70 cubits, 490 palms. X, the rise, is 490
divided by 5.25 or 931⁄3 cubits. These figures sufficed for the
Egyptians and Thales. We would go on to calculate the cotangent as 70
divided by 931⁄3 to get 3/4 or .75 and looking that up in a table
of cotangents find that the angle of rise is a few minutes over
Whether the ability to use the seked, which preceded
Thales by about
1000 years, means that he was the first to define trigonometry is
a matter of opinion. More practically
Thales used the same method to
measure the distances of ships at sea, said Eudemus as reported by
Proclus ("in Euclidem"). According to Kirk & Raven (reference
cited below), all you need for this feat is three straight sticks
pinned at one end and knowledge of your altitude. One stick goes
vertically into the ground. A second is made level. With the third you
sight the ship and calculate the seked from the height of the stick
and its distance from the point of insertion to the line of sight.
The seked is a measure of the angle. Knowledge of two angles (the
seked and a right angle) and an enclosed leg (the altitude) allows you
to determine by similar triangles the second leg, which is the
displaystyle textstyle frac DE BC = frac AE AC = frac AD
Main article: Thales' theorem
Main article: Intercept theorem
See also: Pythagorean theorem
There are two theorems of
Thales in elementary geometry, one known as
Thales' theorem having to do with a triangle inscribed in a circle and
having the circle's diameter as one leg, the other theorem being also
called the intercept theorem. In addition Eudemus attributed to him
the discovery that a circle is bisected by its diameter, that the base
angles of an isosceles triangle are equal and that vertical angles are
equal. According to a historical Note, when
Thales visited Egypt,
he observed that whenever the Egyptians drew two intersecting lines,
they would measure the vertical angles to make sure that they were
Thales concluded that one could prove that all vertical angles
are equal if one accepted some general notions such as: all straight
angles are equal, equals added to equals are equal, and equals
subtracted from equals are equal.
Cosmology: water as a first principle
Thales' most famous philosophical position was his cosmological
thesis, which comes down to us through a passage from Aristotle's
Metaphysics. In the work
Aristotle unequivocally reported
Thales’ hypothesis about the nature of all matter – that the
originating principle of nature was a single material substance:
Aristotle then proceeded to proffer a number of conjectures
based on his own observations to lend some credence to why
have advanced this idea (though
Aristotle didn’t hold it himself).
Aristotle laid out his own thinking about matter and form which may
shed some light on the ideas of Thales, in
Metaphysics 983 b6 8–11,
17–21. (The passage contains words that were later adopted by
science with quite different meanings.)
That from which is everything that exists and from which it first
becomes and into which it is rendered at last, its substance remaining
under it, but transforming in qualities, that they say is the element
and principle of things that are. …For it is necessary that there be
some nature (φύσις), either one or more than one, from which
become the other things of the object being saved...
founder of this type of philosophy says that it is water.
In this quote we see Aristotle's depiction of the problem of change
and the definition of substance. He asked if an object changes, is it
the same or different? In either case how can there be a change from
one to the other? The answer is that the substance "is saved", but
acquires or loses different qualities (πάθη, the things you
Aristotle conjectured that
Thales reached his conclusion by
contemplating that the "nourishment of all things is moist and that
even the hot is created from the wet and lives by it." While
Aristotle's conjecture on why
Thales held water as the originating
principle of matter is his own thinking, his statement that Thales
held it as water is generally accepted as genuinely originating with
Thales and he is seen as an incipient matter-and-formist.
Thales thought the
Earth must be a flat disk which is floating in an
expanse of water.
Heraclitus Homericus states that
Thales drew his conclusion from
seeing moist substance turn into air, slime and earth. It seems likely
Thales viewed the
Earth as solidifying from the water on which it
floated and the oceans that surround it.
Writing centuries later,
Diogenes Laërtius also states that Thales
taught "Water constituted (ὑπεστήσατο, 'stood under') the
principle of all things."
Aristotle considered Thales’ position to be roughly the equivalent
to the later ideas of Anaximenes, who held that everything was
composed of air.
The 1870 book Dictionary of Greek and Roman Biography and Mythology
Thales dogma that water is the origin of things, that is, that it is
that out of which every thing arises, and into which every thing
Thales may have followed Orphic cosmogonies, while,
unlike them, he sought to establish the truth of the assertion. Hence,
Aristotle, immediately after he has called him the originator of
philosophy brings forward the reasons which
Thales was believed to
have adduced in confirmation of that assertion; for that no written
development of it, or indeed any book by Thales, was extant, is proved
by the expressions which
Aristotle uses when he brings forward the
doctrines and proofs of the Milesian. (p. 1016)
Later scholastic thinkers would maintain that in his choice of water
Thales was influenced by Babylonian or Chaldean religion, that held
that a god had begun creation by acting upon the pre-existing water.
Historian Abraham Feldman holds this does not stand up under closer
examination. In Babylonian religion the water is lifeless and sterile
until a god acts upon it, but for
Thales water itself was divine and
creative. He maintained that "All things are full of gods", and to
understand the nature of things was to discover the secrets of the
deities, and through this knowledge open the possibility that one
could be greater than the grandest Olympian.
Feldman points out that while other thinkers recognized the wetness of
the world "none of them was inspired to conclude that everything was
ultimately aquatic." He further points out that
Thales was "a
wealthy citizen of the fabulously rich Oriental port of Miletus...a
dealer in the staples of antiquity, wine and oil...He certainly
handled the shell-fish of the Phoenicians that secreted the dye of
imperial purple." Feldman recalls the stories of
the distance of boats in the harbor, creating mechanical improvements
for ship navigation, giving an explanation for the flooding of the
Nile (vital to Egyptian agriculture and Greek trade), and changing the
course of the river Halys so an army could ford it. Rather than seeing
water as a barrier
Thales contemplated the Ionian yearly religious
gathering for athletic ritual (held on the promontory of Mycale and
believed to be ordained by the ancestral kindred of Poseidon, the god
of the sea). He called for the Ionian mercantile states participating
in this ritual to convert it into a democratic federation under the
protection of Poseidon that would hold off the forces of pastoral
Persia. Feldman concludes that
Thales saw "that water was a
revolutionary leveler and the elemental factor determining the
subsistence and business of the world" and "the common channel of
Feldman considers Thales' environment and holds that
Thales would have
seen tears, sweat, and blood as granting value to a person's work and
the means how life giving commodities travelled (whether on bodies of
water or through the sweat of slaves and pack-animals). He would have
seen that minerals could be processed from water such as
life-sustaining salt and gold taken from rivers. He would’ve seen
fish and other food stuffs gathered from it. Feldman points out that
Thales held that the lodestone was alive as it drew metals to itself.
He holds that
Thales "living ever in sight of his beloved sea" would
see water seem to draw all "traffic in wine and oil, milk and honey,
juices and dyes" to itself, leading him to "a vision of the universe
melting into a single substance that was valueless in itself and still
the source of wealth." Feldman concludes that for
united all things. The social significance of water in the time of
Thales induced him to discern through hardware and dry-goods, through
soil and sperm, blood, sweat and tears, one fundamental fluid
stuff...water, the most commonplace and powerful material known to
him." This combined with his contemporary's idea of "spontaneous
generation" allow us to see how
Thales could hold that water could be
divine and creative.
Feldman points to the lasting association of the theory that "all
whatness is wetness" with
Thales himself, pointing out that Diogenes
Laërtius speaks of a poem, probably a satire, where
snatched to heaven by the sun, "Perhaps it was an elaborate
paronomasia based on the fact that thal was the Phoenician word for
Beliefs in divinity
Neopythagoreanism and Neoplatonism
Thales applied his method to objects that changed to become other
objects, such as water into earth (or so he thought).
applied his method to the act of change itself, approaching it through
lodestone and amber (which, when electrified by rubbing together, also
attracts). As for the ability of a mover to move
something else without being changed itself,
Thales saw a commonality
between that and the power of a living thing to act. The lodestone and
the amber must be alive, and if that were so, there could be no
difference between the living and the dead. When asked why he didn’t
die if there was no difference, he replied "because there is no
Aristotle defined the soul as the principle of life, that which imbues
the matter and makes it live, giving it the animation, or power to
act. The idea did not originate with him, as the Greeks in general
believed in the distinction between mind and matter, which was
ultimately to lead to a distinction not only between body and soul but
also between matter and energy. If things were alive,
they must have souls. This belief was no innovation, as the ordinary
ancient populations of the Mediterranean did believe that natural
actions were caused by divinities. Accordingly,
Aristotle and other
ancient writers state that
Thales believed that "all things were full
of gods." In their zeal to make him the first in everything
some said he was the first to hold the belief, which must have been
widely known to be false. However,
Thales was looking
for something more general, a universal substance of mind.[citation
needed] That also was in the polytheism of the times.
Zeus was the
very personification of supreme mind, dominating all the subordinate
Thales on, however, philosophers had a tendency
to depersonify or objectify mind, as though it were the substance of
animation per se and not actually a god like the other gods. The end
result was a total removal of mind from substance, opening the door to
a non-divine principle of action.
Classical thought, however, had proceeded only a little way along that
path. Instead of referring to the person, Zeus, they talked about the
"Thales", says Cicero, "assures that water is the principle of all
things; and that God is that
Mind which shaped and created all things
The universal mind appears as a Roman belief in
Virgil as well:
In the beginning, SPIRIT within (spiritus intus) strengthens Heaven
The watery fields, and the lucid globe of Luna, and then –
Titan stars; and mind (mens) infused through the limbs
Agitates the whole mass, and mixes itself with GREAT MATTER (magno
According to Henry Fielding,
Diogenes Laërtius (1.35) affirmed that
Thales posed "the independent pre-existence of God from all eternity,
stating "that God was the oldest of all beings, for he existed without
a previous cause even in the way of generation; that the world was the
most beautiful of all things; for it was created by God."
Thales (who died around 30 years before the time of Pythagoras
and 300 years before Euclid, Eudoxus of Cnidus, and Eudemus of
Rhodes) is often hailed as "the first Greek mathematician". While
some historians, such as Colin R. Fletcher, point out that there could
have been a predecessor to
Thales who would've been named in Eudemus'
lost book History of
Geometry it is admitted that without the work
"the question becomes mere speculation." Fletcher holds that as
there is no viable predecessor to the title of first Greek
mathematician, the only question is whether
Thales qualifies as a
practitioner in that field; he holds that "
Thales had at his command
the techniques of observation, experimentation, superposition and
deduction…he has proved himself mathematician."
The evidence for the primacy of
Thales comes to us from a book by
Proclus who wrote a thousand years after
Thales but is believed to
have had a copy of Eudemus' book.
Proclus wrote "
Thales was the first
to go to
Egypt and bring back to Greece this study." He goes on to
tell us that in addition to applying the knowledge he gained in Egypt
"He himself discovered many propositions and disclosed the underlying
principles of many others to his successors, in some case his method
being more general, in others more empirical."
Other quotes from
Proclus list more of Thales' mathematical
They say that
Thales was the first to demonstrate that the circle is
bisected by the diameter, the cause of the bisection being the
unimpeded passage of the straight line through the centre.
[Thales] is said to have been the first to have known and to have
enunciated [the theorem] that the angles at the base of any isosceles
triangle are equal, though in the more archaic manner he described the
equal angles as similar.
This theorem, that when two straight lines cut one another, the
vertical and opposite angles are equal, was first discovered, as
Eudemus says, by Thales, though the scientific demonstration was
improved by the writer of Elements.
Eudemus in his History of
Geometry attributes this theorem [the
equality of triangles having two angles and one side equal] to Thales.
For he says that the method by which
Thales showed how to find the
distance of ships at sea necessarily involves this method.
Pamphila says that, having learnt geometry from the Egyptians, he
[Thales] was the first to inscribe in a circle a right-angled
triangle, whereupon he sacrificed an ox.
In addition to Proclus,
Hieronymus of Rhodes also cites
Thales as the
first Greek mathematician. Hieronymus held that
Thales was able to
measure the height of the pyramids by using a theorem of geometry now
known as the intercept theorem, (after gathering data by using his
walking-stick and comparing its shadow to those cast by the pyramids).
We receive variations of Hieronymus' story through Diogenes
Laërtius, Pliny the Elder, and Plutarch.  Due to the
variations among testimonies, such as the "story of the sacrifice of
an ox on the occasion of the discovery that the angle on a diameter of
a circle is a right angle" in the version told by
being accredited to
Pythagoras rather than Thales, some historians
(such as D. R. Dicks) question whether such anecdotes have any
historical worth whatsoever.
Due to the scarcity of sources concerning
Thales and the diversity
among the ones we possess, there is a scholarly debate over possible
Thales and the Greek mathematicians that came after him.
Historian Roger L. Cooke points out that
Proclus does not make any
mention of Mesopotamian influence on
Thales or Greek geometry, but "is
shown clearly in Greek astronomy, in the use of sexagesimal system of
measuring angles and in Ptolemy's explicit use of Mesopotamian
astronomical observations." Cooke notes that it may possibly also
appear in the second book of Euclid's Elements, "which contains
geometric constructions equivalent to certain algebraic relations that
are frequently encountered in the cuneiform tablets." Cooke notes
"This relation however, is controversial."
Historian B.L. Van der Waerden is among those advocating the idea of
Mesopotamian influence, writing "It follows that we have to abandon
the traditional belief that the oldest Greek mathematicians discovered
geometry entirely by themselves…a belief that was tenable only as
long as nothing was known about Babylonian mathematics. This in no way
diminishes the stature of Thales; on the contrary, his genius receives
only now the honour that is due to it, the honour of having developed
a logical structure for geometry, of having introduced proof into
Some historians, such as D. R. Dicks takes issue with the idea that we
can determine from the questionable sources we have, just how
Thales was by Babylonian sources. He points out that while
Thales is held to have been able to calculate an eclipse using a cycle
called the "Saros" held to have been "borrowed from the Babylonians",
"The Babylonians, however, did not use cycles to predict solar
eclipses, but computed them from observations of the latitude of the
moon made shortly before the expected syzygy." Dicks cites
historian O. Neugebauer who relates that "No Babylonian theory for
predicting solar eclipse existed at 600 B.C., as one can see from
the very unsatisfactory situation 400 years later; nor did the
Babylonians ever develop any theory which took the influence of
geographical latitude into account." Dicks examines the cycle referred
to as 'Saros' - which
Thales is held to have used and which is
believed to stem from the Babylonians. He points out that Ptolemy
makes use of this and another cycle in his book Mathematical Syntaxis
but attributes it to Greek astronomers earlier than
Hipparchus and not
to Babylonians. Dicks notes
Herodotus does relate that
use of a cycle to predict the eclipse, but maintains that "if so, the
fulfillment of the 'prediction' was a stroke of pure luck not
science". He goes further joining with other historians (F.
Martini, J.L. E. Dreyer, O. Neugebauer) in rejecting the historicity
of the eclipse story altogether. Dicks links the story of Thales
discovering the cause for a solar eclipse with Herodotus' claim that
Thales discovered the cycle of the sun with relation to the solstices,
and concludes "he could not possibly have possessed this knowledge
which neither the Egyptians nor the Babylonians nor his immediate
Josephus is the only ancient historian that
Thales visited Babylonia.
Herodotus wrote that the Greeks learnt the practice of dividing the
day into 12 parts, about the polos, and the gnomon from the
Babylonians. (The exact meaning of his use of the word polos is
unknown, current theories include: "the heavenly dome", "the tip of
the axis of the celestial sphere", or a spherical concave sundial.)
Yet even Herodotus' claims on Babylonian influence are contested by
some modern historians, such as L. Zhmud, who points out that the
division of the day into twelve parts (and by analogy the year) was
known to the Egyptians already in the second millennium, the gnomon
was known to both Egyptians and Babylonians, and the idea of the
"heavenly sphere" was not used outside of Greece at this time.
Less controversial than the position that
Thales learnt Babylonian
mathematics is the claim he was influenced by Egyptians. Pointedly
historian S. N. Bychkov holds that the idea that the base angles of an
isosceles triangle are equal likely came from Egypt. This is because,
when building a roof for a home - having a cross section be exactly an
isosceles triangle isn't crucial (as it's the ridge of the roof that
must fit precisely), in contrast a symmetric square pyramid cannot
have errors in the base angles of the faces or they will not fit
together tightly. Historian D.R. Dicks agrees that compared to the
Greeks in the era of Thales, there was a more advanced state of
mathematics among the Babylonians and especially the Egyptians - "both
cultures knew the correct formulae for determining the areas and
volumes of simple geometrical figures such as triangles, rectangles,
trapezoids, etc.; the Egyptians could also calculate correctly the
volume of the frustum of a pyramid with a square base (the Babylonians
used an incorrect formula for this), and used a formula for the area
of a circle...which gives a value for π of 3.1605--a good
approximation." Dicks also agrees that this would have had an
Thales (whom the most ancient sources agree was interested
in mathematics and astronomy) but he holds that tales of Thales'
travels in these lands are pure myth.
The ancient civilization and massive monuments of
Egypt had "a
profound and ineradicable impression on the Greeks". They attributed
to Egyptians "an immemorial knowledge of certain subjects" (including
geometry) and would claim Egyptian origin for some of their own ideas
to try and lend them "a respectable antiquity" (such as the "Hermetic"
literature of the Alexandrian period).
Dicks holds that since
Thales was a prominent figure in Greek history
by the time of Eudemus but "nothing certain was known except that he
lived in Miletus". A tradition developed that as "Milesians were
in a position to be able to travel widely"
Thales must have gone to
Egypt was the birthplace of geometry he
must have learnt that while there. Since he had to have been there,
surely one of the theories on Nile Flooding laid out by
have come from Thales. Likewise as he must have been in
Egypt he had
to have done something with the
Pyramids - thus the tale of measuring
them. Similar apocryphal stories exist of
Pythagoras and Plato
Egypt with no corroborating evidence.
As the Egyptian and Babylonian geometry at the time was "essentially
arithmetical", they used actual numbers and "the procedure is then
described with explicit instructions as to what to do with these
numbers" there was no mention of how the rules of procedure were made,
and nothing toward a logically arranged corpus of generalized
geometrical knowledge with analytical 'proofs' such as we find in the
words of Euclid, Archimedes, and Apollonius." So even had Thales
traveled there he could not have learnt anything about the theorems he
is held to have picked up there (especially because there is no
evidence that any Greeks of this age could use Egyptian
Likewise until around the second century BC and the time of Hipparchus
(c. 194-120 BC) the Babylonian general division of the circle
into 360 degrees and their sexagesimal system was unknown.
Herodotus says almost nothing about Babylonian literature and science,
and very little about their history. Some historians, like P.
Schnabel, hold that the Greeks only learned more about Babylonian
culture from Berossus, a Babylonian priest who is said to have set up
a school in Cos around 270 BC (but to what extent this had in the
field of geometry is contested).
Dicks points out that the primitive state of
Greek mathematics and
astronomical ideas exhibited by the peculiar notions of Thales'
successors (such as Anaximander, Anaximenes, Xenophanes, and
Heraclitus), which historian J. L. Heiberg calls "a mixture of
brilliant intuition and childlike analogies", argues against the
assertions from writers in late antiquity that
Thales discovered and
taught advanced concepts in these fields.
John Burnet (1892) noted
Lastly, we have one admitted instance of a philosophic guild, that of
the Pythagoreans. And it will be found that the hypothesis, if it is
to be called by that name, of a regular organisation of scientific
activity will alone explain all the facts. The development of doctrine
in the hands of Thales, Anaximander, and Anaximenes, for instance, can
only be understood as the elaboration of a single idea in a school
with a continuous tradition.
In the long sojourn of philosophy, there has existed hardly a
philosopher or historian of philosophy who did not mention
try to characterize him in some way. He is generally recognized as
having brought something new to human thought. Mathematics, astronomy,
and medicine already existed.
Thales added something to these
different collections of knowledge to produce a universality, which,
as far as writing tells us, was not in tradition before, but resulted
in a new field.
Ever since, interested persons have been asking what that new
something is. Answers fall into (at least) two categories, the theory
and the method. Once an answer has been arrived at, the next logical
step is to ask how
Thales compares to other philosophers, which leads
to his classification (rightly or wrongly).
The most natural epithets of
Thales are "materialist" and
"naturalist", which are based on ousia and physis. The Catholic
Encyclopedia notes that
Aristotle called him a physiologist, with the
meaning "student of nature." On the other hand, he would have
qualified as an early physicist, as did Aristotle. They studied
corpora, "bodies", the medieval descendants of substances.
Most agree that Thales' stamp on thought is the unity of substance,
hence Bertrand Russell:
The view that all matter is one is quite a reputable scientific
...But it is still a handsome feat to have discovered that a substance
remains the same in different states of aggregation.
Russell was only reflecting an established tradition; for example:
Nietzsche, in his
Philosophy in the Tragic Age of the Greeks,
Greek philosophy seems to begin with an absurd notion, with the
proposition that water is the primal origin and the womb of all
things. Is it really necessary for us to take serious notice of this
proposition? It is, and for three reasons. First, because it tells us
something about the primal origin of all things; second, because it
does so in language devoid of image or fable, and finally, because
contained in it, if only embryonically, is the thought, "all things
This sort of materialism, however, should not be confused with
Thales was only trying to explain the unity
observed in the free play of the qualities. The arrival of uncertainty
in the modern world made possible a return to Thales; for example,
John Elof Boodin writes ("God and Creation"):
We cannot read the universe from the past...
Boodin defines an "emergent" materialism, in which the objects of
sense emerge uncertainly from the substrate.
Thales is the innovator
of this sort of materialism.
Rise of theoretical inquiry
In the West,
Thales represents a new kind of inquiring community as
well. Edmund Husserl attempts to capture the new movement as
follows. Philosophical man is a "new cultural configuration" based in
stepping back from "pregiven tradition" and taking up a rational
"inquiry into what is true in itself;" that is, an ideal of truth. It
begins with isolated individuals such as Thales, but they are
supported and cooperated with as time goes on. Finally the ideal
transforms the norms of society, leaping across national borders.
The term "Pre-Socratic" derives ultimately from the philosopher
Aristotle, who distinguished the early philosophers as concerning
themselves with substance.
Diogenes Laërtius on the other hand took a strictly geographic and
ethnic approach. Philosophers were either Ionian or Italian. He used
"Ionian" in a broader sense, including also the Athenian academics,
who were not Pre-Socratics. From a philosophic point of view, any
grouping at all would have been just as effective. There is no basis
for an Ionian or Italian unity. Some scholars, however, concede to
Diogenes' scheme as far as referring to an "Ionian" school. There was
no such school in any sense.
The most popular approach refers to a Milesian school, which is more
justifiable socially and philosophically. They sought for the
substance of phenomena and may have studied with each other. Some
ancient writers qualify them as Milesioi, "of Miletus."
Influence on others
Thales (Electricity), sculpture from "The Progress of Railroading"
(1908), main facade of Union Station (Washington, DC)
Thales had a profound influence on other Greek thinkers and therefore
on Western history. Some believe
Anaximander was a pupil of Thales.
Early sources report that one of Anaximander's more famous pupils,
Thales as a young man, and that
Thales advised him
to travel to
Egypt to further his philosophical and mathematical
Many philosophers followed Thales' lead in searching for explanations
in nature rather than in the supernatural; others returned to
supernatural explanations, but couched them in the language of
philosophy rather than of myth or of religion.
Looking specifically at Thales' influence during the pre-Socratic era,
it is clear that he stood out as one of the first thinkers who thought
more in the way of logos than mythos. The difference between these two
more profound ways of seeing the world is that mythos is concentrated
around the stories of holy origin, while logos is concentrated around
the argumentation. When the mythical man wants to explain the world
the way he sees it, he explains it based on gods and powers. Mythical
thought does not differentiate between things and persons[citation
needed] and furthermore it does not differentiate between nature and
culture. The way a logos thinker would present a
world view is radically different from the way of the mythical
thinker. In its concrete form, logos is a way of thinking not only
about individualism[clarification needed], but also the
abstract[clarification needed]. Furthermore, it focuses on sensible
and continuous argumentation. This lays the foundation of philosophy
and its way of explaining the world in terms of abstract
argumentation, and not in the way of gods and mythical
Reliability of sources
Thales, Nuremberg Chronicle.
Because of Thales' elevated status in Greek culture an intense
interest and admiration followed his reputation. Due to this
following, the oral stories about his life were open to amplification
and historical fabrication, even before they were written down
generations later. Most modern dissension comes from trying to
interpret what we know, in particular, distinguishing legend from
Historian D.R. Dicks and other historians divide the ancient sources
Thales into those before 320 BC and those after that year
(some such as
Proclus writing in the 5th century C.E. and Simplicius
of Cilicia in the 6th century C.E. writing nearly a millennium after
his era). The first category includes Herodotus, Plato, Aristotle,
Theophrastus among others. The second category
includes Plautus, Aetius, Eusebius, Plutarch, Josephus, Iamblichus,
Diogenes Laërtius, Theon of Smyrna, Apuleius, Clement of Alexandria,
Pliny the Elder, and
John Tzetzes among others.
The earliest sources on
Thales (living before 320 BC) are often
the same for the other Milesian philosophers (Anaximander, and
Anaximenes). These sources were either roughly contemporaneous (such
as Herodotus) or lived within a few hundred years of his passing.
Moreover, they were writing from an oral tradition that was widespread
and well known in the Greece of their day.
The latter sources on
Thales are several "ascriptions of commentators
and compilers who lived anything from 700 to 1,000 years after
his death" which include "anecdotes of varying degrees of
plausibility" and in the opinion of some historians (such as D. R.
Dicks) of "no historical worth whatsoever". Dicks points out that
there is no agreement "among the 'authorities' even on the most
fundamental facts of his life--e.g. whether he was a Milesian or a
Phoenician, whether he left any writings or not, whether he was
married or single-much less on the actual ideas and achievements with
which he is credited."
Contrasting the work of the more ancient writers with those of the
later, Dicks points out that in the works of the early writers Thales
and the other men who would be hailed as "the Seven Sages of Greece"
had a different reputation than that which would be assigned to them
by later authors. Closer to their own era, Thales, Solon, Bias of
Pittacus of Mytilene
Pittacus of Mytilene and others were hailed as "essentially
practical men who played leading roles in the affairs of their
respective states, and were far better known to the earlier Greeks as
lawgivers and statesmen than as profound thinkers and
philosophers." For example,
Plato praises him (coupled with
Anacharsis) for being the originator of the potter's wheel and the
Only in the writings of the second group of writers (working after
320 BC) do "we obtain the picture of
Thales as the pioneer in
Greek scientific thinking, particularly in regard to mathematics and
astronomy which he is supposed to have learnt about in Babylonia and
Egypt." Rather than "the earlier tradition [where] he is a
favourite example of the intelligent man who possesses some technical
'know how'...the later doxographers [such as
Dicaearchus in the latter
half of the fourth century BC] foist on to him any number of
discoveries and achievements, in order to build him up as a figure of
Dicks points out a further problem arises in the surviving information
on Thales, for rather than using ancient sources closer to the era of
Thales, the authors in later antiquity ("epitomators, excerptors, and
compilers") actually "preferred to use one or more intermediaries,
so that what we actually read in them comes to us not even at second,
but at third or fourth or fifth hand. ...Obviously this use of
intermediate sources, copied and recopied from century to century,
with each writer adding additional pieces of information of greater or
less plausibility from his own knowledge, provided a fertile field for
errors in transmission, wrong ascriptions, and fictitious
attributions". Dicks points out that "certain doctrines that later
commentators invented for Thales...were then accepted into the
biographical tradition" being copied by subsequent writers who were
then cited by those coming after them "and thus, because they may be
repeated by different authors relying on different sources, may
produce an illusory impression of genuineness."
Doubts even exist when considering the philosophical positions held to
Thales "in reality these stem directly from Aristotle's
own interpretations which then became incorporated in the
doxographical tradition as erroneous ascriptions to Thales". (The
same treatment was given by
Aristotle to Anaxagoras.)
Most philosophic analyses of the philosophy of
Thales come from
Aristotle, a professional philosopher, tutor of Alexander the Great,
who wrote 200 years after Thales' death. Aristotle, judging from
his surviving books, does not seem to have access to any works by
Thales, although he probably had access to works of other authors
about Thales, such as Herodotus, Hecataeus,
Plato etc., as well as
others whose work is now extinct. It was Aristotle's express goal to
present Thales' work not because it was significant in itself, but as
a prelude to his own work in natural philosophy.
Geoffrey Kirk and
John Raven, English compilers of the fragments of the Pre-Socratics,
assert that Aristotle's "judgments are often distorted by his view of
earlier philosophy as a stumbling progress toward the truth that
Aristotle himself revealed in his physical doctrines." There was
also an extensive oral tradition. Both the oral and the written were
commonly read or known by all educated men in the region.
Aristotle's philosophy had a distinct stamp: it professed the theory
of matter and form, which modern scholastics have dubbed hylomorphism.
Though once very widespread, it was not generally adopted by
rationalist and modern science, as it mainly is useful in metaphysical
analyses, but does not lend itself to the detail that is of interest
to modern science. It is not clear that the theory of matter and form
existed as early as Thales, and if it did, whether
Thales espoused it.
While some historians, like B. Snell, maintain that
relying on a pre-Platonic written record by
Hippias rather than oral
tradition, this is a controversial position. Representing the
scholarly consensus Dicks states that "the tradition about him even as
early as the fifth century B.C., was evidently based entirely on
hearsay....It would seem that already by Aristotle's time the early
Ionians were largely names only to which popular tradition attached
various ideas or achievements with greater or less plausibility".
He points out that works confirmed to have existed in the sixth
century BC by
Xenophanes had already disappeared by
the fourth century BC, so the chances of
surviving to the age of
Aristotle is almost nil (even less likely for
Theophrastus and Eudemus and less likely still for
those following after them).
The main secondary source concerning the details of Thales' life and
Diogenes Laërtius, "Lives of Eminent Philosophers".
This is primarily a biographical work, as the name indicates. Compared
Diogenes is not much of a philosopher. He is the one
who, in the Prologue to that work, is responsible for the division of
the early philosophers into "Ionian" and "Italian", but he places the
Academics in the Ionian school and otherwise evidences considerable
disarray and contradiction, especially in the long section on
forerunners of the "Ionian School".
Diogenes quotes two letters
attributed to Thales, but
Diogenes wrote some eight centuries after
Thales' death and that his sources often contained "unreliable or even
fabricated information", hence the concern for separating fact
from legend in accounts of Thales.
It is due to this use of hearsay and a lack of citing original sources
that leads some historians, like Dicks and Werner Jaeger, to look at
the late origin of the traditional picture of
and view the whole idea as a construct from a later age, "the whole
picture that has come down to us of the history of early philosophy
was fashioned during the two or three generations from
Plato to the
immediate pupils of Aristotle".
Metaphysics Alpha, 983b18.
^ a b Smith, William, ed. (1870). "Thales". Dictionary of Greek
and Roman Biography and Mythology. p. 1016.
^ Michael Fowler, Early Greek Science:
Thales to Plato, University of
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^ a b Frank N. Magill, The Ancient World: Dictionary of World
Biography, Volume 1, Routledge, 2003 ISBN 1135457395
^ (Boyer 1991, "
Ionia and the Pythagoreans" p. 43)
^ a b Cohen, Mark S.; Curd, Patricia; Reeve, C. D. C. (2011). Readings
Philosophy (Fourth Edition): From
Aristotle. Indianapolis, Indiana: Hackett Publishing. p. 10.
^ a b Freely, John (2012). The Flame of Miletus: The Birth of Science
Ancient Greece (And How It Changed the World). London, England: I.
B. Tauris & Co. Ltd. p. 7. ISBN 978-1-78076-051-3.
Retrieved 1 October 2017.
^ Lawson, Russell M. (2004).
Science in the Ancient World: An
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England: ABC CLIO. pp. 234–235. ISBN 1-85109-534-9.
Diogenes Laertius. "Lives of Eminent Philosophers".
^ Nietzsche, Friedrich. "The Pre-Platonic Philosophers".
^ a b Herodotus, 1.74.2, and A. D. Godley's footnote 1; Pliny, 2.9
(12) and Bostock's footnote 2.
Plutarch (1952). "Solon". In Robert Maynard Hutchins. Lives. Great
Books of the Western World. 14. Chicago: William Benton.
Diogenes Laërtius, 1.43, 44.
^ J J O'Connor and E F Robertson,
Thales of Miletus, University of St
Andrews [Retrieved 2016-06-16]
^ Nathan Ida,
Engineering Electromagnetics, Springer, 2015
^ J J O'Connor and E F Robertson
^ Aristotle, Politics 1259a 
^ George Crawford, Bidyut Sen - Derivatives for Decision Makers:
Strategic Management Issues, John Wiley & Sons, 1996
^ Herodotus, Book 1
Diogenes Laërtius 1.25
^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa Dicks, D. R.
(November 1959). "Thales". The Classical Quarterly. 9 (2): 294–309.
Diogenes Laërtius 1.22
^ Laërtius 1925, § 28
^ Geoffrey Stephen Kirk, John Earle Raven, Malcolm Schofield - Les
philosophes présocratiques : Une histoire critique avec un choix
de textes, vol. 16, Fribourg, Saint-Paul, coll.
« Vestigia », 1995 ISBN 978-2-204-05263-4
^ Plutarch, De Pythiae oraculis, 18.
^ Farrington, B., 1944 Greek Science. Pelican
^ Garrett Thomson,
Thales to Sextus: An Introduction to Ancient
Philosophy, page 25, Waveland Press, 2015, ISBN 1478631864
^ Patricia O'Grady,
Thales of Miletus, Internet Encyclopedia of
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^ English physics comes from it, but the latter is a Greek loan. In
addition the quite ancient native English word be comes from the same
^ The initial g of the archaic Latin gives the root away as *genə-,
^ Laërtius 1925, § 35
^ Shute, William George; Shirk, William W.; Porter, George F. (1960).
Solid Geometry. American Book Company.
^ Aristotle. Metaphysics. 983 b6 8-11.
^ Chisholm, Hugh, ed. (1911). "
Thales of Miletus". Encyclopædia
Britannica (11th ed.). Cambridge University Press.
Diogenes Laërtius. paragraph 27. Missing or empty title=
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West and South. 41 (1): 4–6. ISSN 0009-8353.
^ Aristotle. De Anima. p. 411a7.
^ Kirk, G. S.; Raven, J. E.; Schofield, M. (December 29, 1983). The
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^ Cicero. De Natura Deorum. p. i.,10.
^ Virgil. "vi". Aeneid. pp. 724–727.
^ Fielding, Henry (1775). An essay on conversation. John Bell.
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^ Laërtius 1925, §27.
^ Plutarch, Moralia, The Dinner of the Seven Wise Men, 147A
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^ Burnet, John (1892). Early Greek Philosophy. p. 29.
^ Turner, Catholic Encyclopedia.
^ Wisdom of the West
^ § 3
^ The Vienna Lecture
^ See Aristotle,
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^ Kirk and Raven, The Presocratic Philosophers, Second Edition
(Cambridge University Press, 1983) 3.
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Texts Online site.
^ See McKirahan, Richard D., Jr. (1994).
Philosophy Before Socrates.
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Aristotle (2nd ed.). p. 454.
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A. D. Godley (translator), Cambridge: Harvard
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On the Sizes and Distances (Aristarchus)
On the Heavens
On the Heavens (Aristotle)
Circle of latitude
Deferent and epicycle
Medieval European science
Medieval Islamic astronomy
Ancient Greek mathematics
Aristaeus the Elder
Isidore of Miletus
Theon of Alexandria
Theon of Smyrna
Zeno of Elea
Zeno of Sidon
On the Sizes and Distances (Aristarchus)
On Sizes and Distances
On Sizes and Distances (Hipparchus)
On the Moving Sphere (Autolycus)
The Sand Reckoner
Problem of Apollonius
Squaring the circle
Doubling the cube
Library of Alexandria
Ancient Greek mathematicians
Pre-Socratic philosophers by school
Ancient Greek schools of philosophy
Zeno of Elea
Diogenes of Sinope
Euclid of Megara
Phaedo of Elis
Apollonius of Tyana
Zeno of Citium
Greek Dark Ages
Ancient Greek colonies
Antigonid Macedonian army
Army of Macedon
Sacred Band of Thebes
List of ancient Greeks
Kings of Argos
Archons of Athens
Kings of Athens
Kings of Commagene
Kings of Lydia
Kings of Macedonia
Kings of Paionia
Attalid kings of Pergamon
Kings of Pontus
Kings of Sparta
Tyrants of Syracuse
Diogenes of Sinope
Alexander the Great
Milo of Croton
Philip of Macedon
Ancient Greek tribes
Funeral and burial practices
Arts and science
Greek Revival architecture
Funeral and burial practices
Theatre of Dionysus
Tunnel of Eupalinos