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Thales of Miletus: The First Greek Philosopher

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Thales of Miletus

Thales of Miletus

During the first millennium BC Greeks migrated eastward across the Aegean Sea to settle in what is now western Turkey. The Greeks claimed to be descendants of a man named Ion and called the area they settled Ionia. Around the coastal city of Miletus, ancient Mesopotamian learning and Greek culture merged in the sixth century BC to establish what we now call the Ionian Enlightenment. This enlightenment was something akin to the European Enlightenment of the 18th century AD. The two eras had in common advances in scientific thought, accepting naturalist explanations to understand the world rather than relying on supernatural or mystical reasons, and the application of rational deterministic thought to the physical world. One significant difference between the two eras was that in Miletus, such principles came to fruition for the first time in a Western culture.

The coastal city of Miletus on the Aegean Sea was on the trade routes of the merchants who sailed the Mediterranean Sea; as a result, the city saw visitors from many different parts of the known world. Three men from Miletus—Thales, Anaximander, and Anaximenes—stand out as seekers of knowledge, men who questioned the old way of thinking about the world and started to rely on rational thought to understand natural phenomenon rather than see their lives as being controlled by the whims of the mythical gods. The Milesian thinkers began to incorporate what they learned from the sages of Egypt and Babylonia in three important ways. First, they began to ask not so much how things worked but rather why: What force was behind the motion of the planets across the night sky? Why did the rain fall from the sky? Why did the Sun rise in the east each day? And a thousand other questions. Secondly, the Milesians articulated the idea of “natural causes”; that is, that nature is independent from the will of the capricious gods. Lastly, the wise thinkers began to propose theories to explain the cosmos. The eldest of these thinkers was Thales, whom we now call the first philosopher and scientist of the Western tradition.

Sources of Information About Thales

Since Thales of Miletus left no known written works, what we know of the man comes from various ancient sources who lived hundreds of years after his death. Most of what we know of the man and his teachings comes from the fourth century BC philosopher Aristotle, the fourth century BC Greek historian Herodotus, and the third century AD biographer Diogenes Laërtius. Other ancient authors have also provided glimpses into the life, work, and time of Thales; however, each bit of information we know of the man and his ideas should be taken with a degree of skepticism as the ancient sources are all secondary and of questionable veracity.

The Life of Thales

The birth of Thales is estimated to be around 625 BC and, according to Diogenes Laërtius, “Thales…was the son of Euxamius and Cleobule; of the family of the Thelidae, who are Phoenicians by descent, among the most noble of all the descendants…And he was the first man to whom the name of Wise was given…in whose time also the seven wise men had that title given to them.” Also, according to Laërtius, Thales may have been married and had children. “Some assert that he was married, and that he had a son name Cibissus; others, on the contrary, say that he never had a wife, but that he adopted the son of his sister; and that once being asked why he did not himself become a father, he answered, that it was because he was fond of children.” Though little is known of his upbringing, it is thought that he traveled to Egypt for part of his education. During his adulthood he was active in public affairs in Miletus, including acting as an advisor on maintaining peace with the Lydians. On the death of Thales, Laërtius records, “He [Thales] died at the age of seventy-eight years, or according to the statement of Sosicrates, at the age of ninety, for he died in the fifty-eighth Olympiad…” As the story goes, Thales died of heat prostration while a spectator at the Olympic games. The information that is available about the death of Thales places the year around 548/545 BC.

Map of ancient Greece showing Miletus (Myletus) on the western coast of modern-day Turkey.

Map of ancient Greece showing Miletus (Myletus) on the western coast of modern-day Turkey.

The Story of the Olive Press

Aristotle relates a story of Thales’ practical knowledge and entrepreneurial spirit that has been recounted by other ancient authors. According to Aristotle, Thales had been reproached for being impractical since he spent his time observing the heavens and pondering deep things. Thales proved his detractors wrong by using his knowledge of astronomy and nature to predict a bumper crop of olives in the coming season. Olives were valuable commodities as they were a food stuff, and the oil was used for cooking and as fuel for oil lamps. To extract the valuable oil from the olive, mechanical presses were needed to squeeze the fruit until it gave up its oil. Thales, predicting a bountiful crop of olives for the approaching season, gathered his money and purchased as many olive presses as he could afford. When the bountiful crop appeared, all of the producers needed the presses to process their harvest. Thales was able to sell or rent the presses to other growers at a handsome profit. According to Aristotle in his work Politics (1259a), “Thus he showed the world that philosophers can easily be rich if they like, but that their ambition is of another sort.”

Piece of an ancient wine or olive press.

Piece of an ancient wine or olive press.

Thales Falls into a Well

The philosopher Plato tells the story of Thales being so absorbed in walking at night and looking at the starry sky that he accidentally falls into a well. In Plato’s work Theaetetus (174a), Socrates is trying to illustrate a point using the example of Thales, “I will illustrate my meaning, Theodorus, by the jest which the clever witty Thracian handmaid is said to have made about Thales, when he fell into a well as he was looking up at the stars. She said that he was so eager to know what was going on in heaven, that he could not see what was before his feet.”

Prediction of an Eclipse of the Sun

One astronomical prediction Thales is credited with is still puzzling historians and astronomers today. The oldest source of the story comes from the Greek historian Herodotus, who tells that Thales predicted a solar eclipse that had a decisive impact on the Battle of Halys between the Lydians and the Medes. According to Herodotus, at the climax of a lengthy war for control of present-day Turkey, “A battle took place in which it happened, when the fight had begun, that suddenly the day became night. And this change of the day Thales the Milesian had foretold. The Lydians, however, and the Medes, when they saw that it had become night instead of day, ceased from their fighting and were much more eager, both of them, that peace should be made between them.” Modern astronomers have now determined that an eclipse occurred on May 28, 585 BC, at the location of the battle. One theory as to how Thales was able to perform this amazing astronomical prediction was by the use of the “Babylonian saros,” a cycle of 223 lunar months, after which eclipses of both the sun and the moon repeat. Since it is still not known how Thales made this prediction of the eclipse with only minimal scientific data available, it may have been strictly a lucky guess! As a result of the eclipse, fighting stopped immediately and the two sides established a truce. As pointed out by the science writer Isaac Asimov, knowing the exact date of the eclipse rendered the Battle of Halys the first ancient historical event that is known to the exact day.

Geometry

We learn of Thales’ accomplishments in mathematics, in particular geometry, from a source that lived roughly a thousand years after Thales, Proclus. What we know of Thales’ work in mathematics comes from Eudemus of Rhodes, who was a student of Aristotle. Eudemus wrote a history of mathematics in the fourth century BC, which has been lost, but parts of his book did make it into a fifth century AD book by the philosopher Proclus, who reported that, “Thales, who had travelled to Egypt, was the first to introduce this science into Greece. He made many discoveries himself and taught the principles for many others to his successors, attacking some problems in a general way and others more empirically.” Proclus tells us that Thales is credited with the discovery of five theorems in geometry.


Theorem 1 - The angle inscribed in a semi-circle is a right angle. This is known as Thales' Theorem.

Theorem 1 - The angle inscribed in a semi-circle is a right angle. This is known as Thales' Theorem.

Theorem 2 - A circle is bisected by a diameter.

Theorem 2 - A circle is bisected by a diameter.

Theorem 3 - The base angles of an isosceles triangle are equal.

Theorem 3 - The base angles of an isosceles triangle are equal.

Theorem 4 - The pairs of vertical angles formed by two intersecting lines are equal.

Theorem 4 - The pairs of vertical angles formed by two intersecting lines are equal.

Theorem 5 - If two triangles are such that two angles and a side of one are equal respectively to two angles and a side of the other, then the triangles are congruent (equal).

Theorem 5 - If two triangles are such that two angles and a side of one are equal respectively to two angles and a side of the other, then the triangles are congruent (equal).

Thales’ Cosmology

Like the other Milesian philosophers, Thales spent much of his intellectual energy trying to understand the mechanisms that governed the cosmos. What we know of Thales’ cosmology comes from a few passages in Aristotle’s Metaphysics and On the Heavens. Aristotle relates that Thales believed that the earth floats on water. Thales used the idea of a floating earth to explain why earthquakes occur, breaking with the traditional view that the god Poseidon was responsible for earthquakes. Even though Thales’ explanation of earthquakes is totally incorrect, it does display a logical cause and effect relationship, which is one of the bedrock principles in modern science.

According to Aristotle, Thales believed that water was the principal substance, or arche in ancient Greek. In Metaphysics (983) Aristotle wrote, “Thales, the founder of this type of philosophy, says the principle is water (for which reason he declared that the earth rests on water), getting the notion perhaps from seeing that the nutriment of all things is moist, and that heat itself is generated from the moist and kept alive by it (and that from which they come to be is a principle of all things).” Thales might have come to this conclusion by several observations, perhaps as Aristotle suggests that the nutriments of life are warm and moist, or perhaps it was his observations of the changing states of water, from the solid state of ice to water, from liquid state to steam or mist, or perhaps living near the sea he saw the importance of water to everyday life.

Thales as the First Philosopher

Aristotle’s claim that Thales was the first philosopher brings up the question, can this claim be justified? Like his fellow Milesian philosophers, Thales abandoned long held beliefs that the supernatural gods ruled the physical world, rather believing natural explanations held sway. Thales adhered to two crucial principles that set him apart from his predecessors. First, he sought natural as opposed to supernatural explanations to natural phenomena. Secondly, he formulated a unifying hypothesis to explain and tie observations together. The fact that Thales adhered to both these principles makes him influential in opening the door for the development of science, thus lending credence to Aristotle’s assertion that Thales was the first philosopher. Lobon of Argos, a third century BC Greek poet, paid tribute to Thales, stating, “Miletus, fairest of Ionian cities; Gave birth to Thales, great astronomer; Wisest of mortals in all kinds of knowledge.”

References

  • Boyer, Carl B. and Uta C. Metzbach. A History of Mathematics. Second Edition. New York: John Wiley & Sons, Inc., 1991.
  • Laertius, Diogenes and C.D. Yonge (Translator). The Lives and Opinions of Eminent Philosophers. London: G. Bell and Sons, Ltd., 1915.
  • Morris, Ian and Barry B. Powell. The Greeks: History, Culture, and Society. Second Edition. Prentice Hall, 2010.
  • Morrow, Glenn R. Proclus A Commentary on the First Book of Euclid’s Elements. Princeton: Princeton University Press, 1970.
  • Taylor, A.E. Plato: The Man and His Work. Mineola: Dover Publications, Inc., 2001.
  • The Encyclopedia Americana, International Edition. New York: Americana Corporation, 1968.
  • The New Encyclopedia Britannica. Chicago: Encyclopedia Britannica, Inc., 1994.
  • Warner, Rex. The Greek Philosophers. New York: New American Library, 1986.
  • West, Doug. The Ancient Milesian Philosophers: Thales, Anaximander, Anaximenes: A Short Introduction to Their Lives and Work. Missouri: C&D Publications. 2021.
  • Plato and Benjamin Jowett (translator). Theaetetus. The Internet Classics Archive. http://classics.mit.edu/Plato/theatu.html. Accessed March 3, 2021.

Comments

Doug West (author) from Missouri on May 04, 2021:

Fran:

Thanks for the comment. It has always amazed me that Thales doesn't get much credit for being the first natural philosopher. Plato and Aristotle are the headliners from that era.

fran rooks from Toledo, Ohio on May 04, 2021:

Doug, what an interesting and informative article. I certainly learned something new from your article. The name Thales was new to me. Thanks for sharing.

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