Some scholars credit Thales of Miletus as the father of Western philosophy since he preceded Socrates, Plato, Aristotle, and other more famous philosophers.

From a chronological point of view, this is true. He was indeed the first philosopher who laid the foundations of Greek philosophical thinking since he was born roughly two centuries earlier than all of the above.

Little to nothing is known about his date of birth and life. His parents were Examyas and Cleobulina and were likely wealthy. He was born in the ancient Greek Ionian city of Miletus in Anatolia. His estimated date of birth ranges from 626 to 620 BC and his death from 645 to 542 BC. There is nothing surviving of Thales’ work. Everything we know about him comes from later sources, some of which are not very reliable. We also know that in ancient times, history was interwoven with mythology.

Aristotle (384-322 BC) was the first to call Miletus the “First Philosopher” for his systematic method, accurate pronouncements, and, quite importantly, for introducing deductive reasoning.

Thales was credited for being one of the seven sages of ancient Greece. Other notable figures alongside Thales were Pittacus of Mytilene, Solon of Athens, and Bias of Priene. There are three more who are usually on the list, including Chilon of Sparta, Cleobulus of Lindos, and Periander of Corinth. Since the last three were known as tyrants, they were often replaced by more agreeable names such as those of Anacharsis, Myson of Chenae, or Pythagoras.

Thales contributed greatly not only to Western philosophy but also to mathematics, geometry, and astronomy as well. He was the first to break the tradition of using mythology to explain the physical world.

Theory in practice

Unlike most philosophers, Thales of Miletus was not only interested in theorizing. He liked to test his theories in practice, too. He famously counted the height of the Great Pyramid of Giza by studying its shadow.

On a more practical side, Herodotus wrote that he assisted the army of King Croesus of Lydia to cross the river Halys by simply instructing them to dig a dam that divided the river into two easy-to-cross straits.

More importantly, the Ionian philosopher was attributed with five theorems in geometry, including the famous one simply known as the “Thales Theorem.”

Thales is said to have accurately predicted the solar eclipse of May 28, 585 BC. He also observed and studied constellations. It was a feat that would prove useful in sea navigation. His third most important astronomical achievement was the determination of the sun’s course from one solstice to the next.

Thales traveled to Egypt to study. The Egyptians were experts in geometry, as pyramid constructions prove. The expertise Thales developed on geometry had its roots in Egypt since the Egyptians were the first to develop the particular science. Furthermore, the Milesians had established a prosperous trading colony in Egypt, namely Naucratis. Therefore, it would have been easy for the philosopher to travel there.

According to Proclus of Athens (*412–485 C.E.), later quoted by Thomas Little Heath:

“Thales…first went to Egypt and hence introduced this study [geometry] into Greece. He discovered many propositions himself, and instructed his successors in the principles underlying many others, his method of attack being in some cases more general, in others more empirical.”

Another one of Thales’ achievements was his measuring of the height of the Great Pyramid of Giza. His philosophy, exhibiting knowledge of the Egyptian views on cosmogony, is further proof of his travels.

Perhaps Thales learned the practical applications of geometry and mathematics from the Egyptians. The Egyptians had great practical skills, but they had little to do with abstract thought. The Greek philosopher would observe the land surveyors, those who used a knotted cord to make their measurements. They are otherwise known as rope-stretchers.

Egyptian mathematics had already reached its heights when The Rhind Mathematical Papyrus was written in about 1800 BC. More than a thousand years later, Thales would have likely watched the surveyors as they went about their work in the same manner: measuring the land using a knotted rope that they stretched to measure lengths and form angles.

Thales of Miletus philosophy

Scholars classify Thales’ philosophy as materialist monism. Substance monism is based on the idea that the world is created by one substance. For Thales of Miletus, this was water. He believed that matter, in the form of water, was above abstract ideas. In that respect, he was also a materialist. He held that the primary source of everything was to be found in water. The world was made of water and, at some point, everything would return to water.

Even though that was a difficult notion to grasp in his time, we can’t deny that water is one of the most necessary components for the existence of life. There is no life without water. Likewise, there is no planet Earth without the element. About 2,600 years later, scientists have found that the planet was completely covered in water 2.5 to 4.0 million years ago.

Looking for answers in the cosmogony of the ancient Greeks and Egyptians, Thales probably found a common pattern. Both civilizations, for instance, revered water as a force of regeneration. In his poems, Homer considered gods of water such as Oceanus and Tethys the parents of all divine beings.

Thales believed the Earth floated on water and that earthquakes occurred as a result of the oceans’ turbulence. In Greek mythology, the god of the seas, Poseidon, was also called “the Earth Shaker” and was considered to be the one responsible for earthquakes.

However, Thales did not believe in the divine cause of natural phenomena. His hypotheses indicate that he saw phenomena as natural events with natural causes and possible explanations. From his new perspective of observation and reasoning, the Ionian philosopher studied the heavens and sought explanations of heavenly phenomena.

Milesian school of philosophy

The first three philosophers in the Western tradition were all cosmologists from Miletus, and Thales was the pioneer. He was followed by Anaximander, who was, in turn, followed by Anaximenes. They established what came to be known as the Milesian school of thought.

According to ancient sources, Thales had been the “teacher and kinsman” of Anaximander. Rather than water, Anaximander held that all was made of apeiron or the infinite. Aneximenes,  perhaps following the line of his predecessors, believed everything was composed of air.

Thales’ hypotheses were rational and scientific. He was the first who sought knowledge for its own sake. To the Ionian philosopher, the world owes the development of the scientific method, as he was the first to adopt practical methods before general principles.