You might be familiar with the works of Aristotle, Socrates, and Plato due to their contributions as early Greek scholars. Have you ever heard about Anaximander, the first philosopher to make massive changes to the astronomical world and natural philosophy?
He was a pre-Socratic philosopher, predating the typical study of Greek scholars. That’s probably why you never heard of him.
When studying ancient Greek thinkers, it is natural to place them in specific categories including philosopher, astronomer, biologist, or physician. Two thousand years ago these distinctions didn’t exist. The great minds of the ancient world seldom limited themselves to a specific topic of study, as we do today. For them, there was no distinction between what we now call “science” and “philosophy.”
The line between science and philosophy can often be a blurred one. The difference is that science depends on observations and experimentation, and it produces a “result,” whereas philosophy depends on logical arguments and doesn’t necessarily have to produce a “result.”
Anaximander of Miletus, a thinker of the pre-Socratic era, is a remarkable figure in the history of philosophy and astronomy. Living around 610-546 BCE in the ancient Greek city of Miletus, Anaximander made profound contributions to cosmology, biology, and metaphysics.
His philosophical ideas laid the foundation for a more rational and systematic approach to understanding the natural world, marking a significant shift from mythological explanations to early scientific thought.
In the 2017 essay collection Anaximander in Context: New Studies on the Origins of Greek Philosophy, Dirk Couprie, Robert Hahn, and Gerald Naddaf describe Anaximander’s mind as “one of the greatest minds in history.” Couprie goes on to state that he considers him on par with Newton.
Anaximander is the first scholar to write a book on Natural Philosophy, which paved the path for many contemporary philosophers. His book “On Nature” argued for the concept of the Aperion.
The apeiron concept is his most enduring contribution to philosophy. He postulated that an underlying, boundless, and indefinite principle was the source of all things. According to Aristotle and Theophrastus, the first Greek philosophers were looking for the “origin” or “principle” (the Greek word “archê” has both meanings) of all things. Anaximander identified it with “the Boundless” or “the Unlimited” (Greek: “Apeiron,” that is, “that which has no boundaries”).
“Everything has an origin or is an origin. The Boundless has no origin. For then, it would have a limit. Moreover, it is both unborn and immortal, a kind of origin. For that which has become has also, necessarily, an end, and there is a termination to every process of destruction”.
Most of this book is unidentified as the fragments are lost in time. A primary source is his successor, Theophrastus, who referenced some parts of “On Nature” and was a follower of Anaximander’s accounts of Geography, Biology, and Astronomy.
Anaximander never fully or clearly explained explain what he meant by “the Boundless.” More recently, authors have disputed whether the Boundless should be interpreted spatially or temporarily without limits, perhaps as that which has no qualifications or as inexhaustible. Some scholars have even defended the meaning as:
“That which is not experienced” by relating the Greek word “Apeiron” not to “peras” (“boundary,” “limit”) but to “perao” (“to experience,” “to apperceive”).
The Greeks in those days were familiar with the idea of the immortal Homeric gods. Anaximander added two distinctive features to the concept of divinity:
• Boundless is an impersonal something, and
• Boundless is not only immortal but also unborn.
“All the heavens and the worlds within them” have sprung from “some boundless nature.”
This concept directly challenged prevailing mythological explanations for the origins of the cosmos.
Anaximander’s life and background are essential for understanding his philosophical contributions. Born in Miletus, a thriving city of Ionia, he was a contemporary of Thales, another prominent pre-Socratic philosopher. His background likely included exposure to the cosmopolitan culture of Ionia and its connection to the broader Mediterranean world.
Anaximander is credited as the first Greek geographer to attempt the map of our world, at least according to ancient observers. It was not unusual to use regional maps in the olden times. However, the thought of mapping out the whole globe was much more novel. Only after Anaximander started this endeavor, Hecataeus of Miletus, who was a traveler, attempted making the perfect map out of his predecessor’s creation while improving on it.
He did not restrict his thinking to astronomy and geography. Anaximander extended his philosophical inquiries into the realm of biology. He theorized about evolution, concluding that life first arose in wet rather than dry conditions. He sought to explain the origins and development of life, suggesting that humans and animals evolved from simpler forms. His ideas were among the earliest precursors to the theory of evolution.
Anaximander developed a unique cosmological model that challenged traditional beliefs about the Earth’s centrality in the cosmos.
He proposed a universe where the Earth was not at the center but a celestial body in its own right. Three propositions, which make up the core of Anaximander’s astronomy, are a tremendous jump forward and constitute the origin of our Western concept of the universe. His astronomical speculations are as follows:
Celestial bodies make full circles and pass beneath the Earth. 
The Earth floats free and unsupported in space.
The celestial bodies lie behind one another.
The idea that the celestial bodies, in their daily course, make complete circles and thus pass beneath the Earth – from Anaximander’s viewpoint – is so self-evident to us that it is hard to understand how daring its introduction was.
That the celestial bodies make full circles is not something he could have observed but a conclusion he must have drawn.
His cosmological ideas laid the foundation for future astronomers and philosophers to explore the universe’s structure.
Among many of his other inventions, Anaximander was also responsible for introducing the gnomon and sundial into Greek culture. He traveled to Sparta to set up a gnomon, a simple pillar that is fixed straight over markings on the ground, representing a dial. Based on the shadows cast by the pillar and their interaction with the markings, one could accurately tell the time.
His philosophical ideas left a lasting imprint on the development of Greek thought and Western philosophy. He was crucial in the transition from mythological explanations to a more systematic and rational approach to understanding the natural world.
Anaximander of Miletus stands as a foundational figure in the history of philosophy. His ideas on the apeiron, cosmology, and biology challenged traditional beliefs and paved the way for future generations of thinkers to explore the mysteries of the universe.
His legacy survives as a testament to human curiosity, intellectual courage, and the timeless quest for understanding the world in which we live.
He is our latest ECG Hall of Fame Library addition. 
Sources:
World History Encyclopedia – Joshua J. Mark
Internet Encyclopedia of Philosophy
Wikipedia