Life and Work

Thales of Miletus (c. 624–546 BC), often celebrated as the "father of philosophy," was a pre-Socratic thinker whose intellectual pursuits laid the groundwork for Western philosophy. Thales is also credited as the founder of the Milesian school of natural philosophy, which sought to explain the nature of the world without resorting to mythology. Among the Seven Sages of Greece, Thales stands out not only for his philosophical contributions but also for his work in astronomy, mathematics, and engineering.

Despite his profound influence, very little of Thales' own writings have survived. The scant references to his work come from later authors, who sometimes ascribed works to him without clear justification. For example, some ancient sources mention a work titled Nautical Star-guide, though its attribution to Thales is questionable. Other accounts suggest that he authored just two works: On the Solstice and On the Equinox. However, even these titles remain speculative, as no direct excerpts or manuscripts have survived to confirm their existence.

Astronomy and Mathematics

Thales' reputation as a thinker was not confined to philosophy alone; he was also a pioneering astronomer and mathematician. One of his most remarkable achievements was predicting a solar eclipse in 585 BC, an event that significantly elevated his stature in the ancient world. This prediction demonstrated not only his understanding of celestial cycles but also the application of scientific reasoning, setting him apart from his contemporaries.

Thales' contributions to mathematics are equally noteworthy. He is credited with several fundamental theorems, including the one that states a circle is bisected by its diameter. Proclus, a later Greek philosopher, attributed three key geometrical theorems to Thales:

1. A circle is bisected by its diameter.

2. The angles at the base of an isosceles triangle are equal.

3. Vertically opposed angles formed by two intersecting lines are equal.

These theorems laid the foundation for what would become known as Euclidean geometry, underscoring Thales' pivotal role in the development of mathematical thought.

Thales was also a keen traveler, and his explorations had practical implications for his work. Herodotus, the ancient historian, recorded an anecdote where Thales measured the height of the Egyptian pyramids by observing their shadows at the moment when his own shadow was equal to his height. This story highlights Thales' ingenuity and his ability to apply mathematical principles to solve real-world problems.

The Primacy of Water

In addition to his contributions to mathematics and astronomy, Thales is renowned for his philosophical inquiry into the nature of the universe. He is credited as the first Greek philosopher to propose a fundamental principle, or arche, that underlies all of existence. Thales identified this primary substance as water (hydor), positing that everything in the universe originated from this essential element.

Thales' reasoning likely stemmed from the observation that water is indispensable for life and is found in various forms throughout nature—liquid, solid, and vapor. Water's ubiquity and its crucial role in sustaining life probably led Thales to conclude that it was the source of all things. Some scholars suggest that Thales was influenced by the Homeric view of the world, particularly the idea of Oceanus, the divine river encircling the earth, as the source of all life, both mortal and immortal. According to this perspective, Thales envisioned the earth itself as floating on water, much like a raft.

Pantheism and the Soul

Thales' monistic view of water also led him to a form of animistic pantheism. If water is the divine source of all life, then it follows that the entire universe, both animate and inanimate, is infused with life or divinity. Thales thus suggested that the world is "full of gods," a notion that Aristotle later interpreted as indicating that Thales believed the soul, or life force, was intermixed with the universe and that this force was water itself.

This idea, that the soul and the substance of nature are one and the same, represents a significant philosophical leap. It implies a kinetic power inherent in water, capable of generating movement and life. For Thales, water was not just a physical substance but also a spiritual one, embodying both the material and the divine aspects of existence.

Legacy and Testimonies

Thales' ideas were preserved and transmitted largely through the writings of later philosophers, particularly Aristotle. In Metaphysics (983b6), Aristotle acknowledged Thales as the founder of natural philosophy and credited him with the idea that water is the fundamental substance from which all things originate. Aristotle also referenced Thales' belief that the universe is full of gods in De Anima (IIa7), linking this idea to Thales' view of the soul as intermingled with the cosmos.

Thales' legacy is one of intellectual curiosity and innovation. As the first known philosopher to seek natural explanations for the phenomena of the world, he set the stage for subsequent generations of thinkers. His belief in a single underlying principle marked the beginning of a shift from mythological to rational explanations of the universe—a shift that would define the trajectory of Western philosophy for centuries to come.

In conclusion, Thales of Miletus was a pioneering figure whose inquiries into the nature of the universe, coupled with his mathematical and astronomical achievements, established him as a foundational thinker in Western philosophy. His identification of water as the primary substance, his geometric theorems, and his early form of pantheism are testaments to his enduring influence on the development of human thought.