Anaximander lived in the vibrant Ionian city of Miletus, a wealthy hub of trade and culture on the Aegean coast. In this environment of prosperity and contact with foreign ideas, a new kind of thinking emerged—one that asked what the world was made of, not in the language of gods and monsters, but in terms of nature and observation. This intellectual movement, sometimes called the Ionian Awakening, marked the birth of Western philosophy.

As a student of Thales, Anaximander was shaped by the notion that the universe could be understood through natural causes. Thales believed that everything originated from water, a bold departure from mythology. Yet Anaximander questioned this idea—not with defiance, but with thoughtful refinement. He asked: could a single substance like water really be the source of all things? His respectful disagreement signals the beginning of philosophical dialogue and evolution.

In place of any one element, Anaximander proposed the apeiron—a term meaning "the infinite" or "the boundless." This was not water, fire, or any other identifiable thing, but something indefinite and eternal from which everything emerges and to which everything returns. The apeiron wasn’t a material substance, but a principle—a radical idea at the time. It introduced a concept of origin that transcended form and opened the door to abstract thought.

Anaximander believed that nature operated according to its own kind of justice. He wrote that things “pay penalty and retribution to each other for their injustice,” suggesting that when one force—like fire or water—oversteps, the universe rebalances over time. This idea of a self-correcting, ordered cosmos was deeply innovative. Instead of divine punishment, he offered a kind of natural ethics, where balance was restored through necessity, not intervention.

Long before Darwin, Anaximander looked at human vulnerability—especially in infancy—and reasoned that we couldn’t have emerged in our current form. He theorized that life began in water, and that humans evolved from fish-like creatures more suited to early survival. It was a shocking departure from traditional origin stories, offering instead a naturalistic explanation grounded in observation and logic.

Anaximander also proposed that the Earth did not rest on anything but remained suspended in space, held in place by symmetry and balance. He imagined it as a thick cylinder—floating freely, not supported by gods or held up by water. His model of the cosmos included rings of fire surrounding the Earth, with the sun, moon, and stars shining through holes in those rings. Though inaccurate, it was one of the first attempts to describe the heavens in physical terms.