Anaximander, many Substances and Harmonious Conflict

Thales was mentor to a younger generation of aristocratic thinkers, and among his disciples was Anaximander, also of Miletus, who lived from approximately 611 to around 547. He wrote a book entitled On Nature but none of his writing survives. What we know of him comes from summaries by other writers, especially Aristotle and Theophrastus.

Anaximander was on the same track as Thales, concerned with a primary source as was Thales, but he rejected the idea that the fundamental essence of all things is a particular substance or what he defined as substance in general. Substance, he declared, is derived. The primary source he and Thales were interested in, he claimed, was not derived from anything.

He saw substance in conflict with substance, substances contending against one another. He saw conflict in nature, force meeting force, defeating one another, wetness against dryness, heat against cold, night against day and day against night, an endless cycle -- and a confusion between abstractions such as day and materiality. He saw the opposing pairs as governing the universe in an endless temporal succession, producing a harmony that derived from their having a common source: the primary source.

His primary source was infinite and eternal. Infinity and eternity are difficult if not impossible to visualize, but Anaximander at least grasped it as an idea, as had the Egyptians -- an idea that rivaled that which he rejected: that something could be created out of nothing.

Like Thales, Anaximander dabbled in mathematics and made contributions to geometry. Various inventions, including the sundial, have been attributed to him. And, like Thales, his interest in the world led him to travel. His travels led him to make a contribution to geography. He is said to have been the first to map what the Greeks knew of the world.

In an effort to see the heavens clearly and rationally, he attempted to map the distribution of celestial bodies. He theorized that the earth was at rest in the center of space, but that beyond this there could be countless other worlds.

He speculated that early in its history the earth was covered with water, as indicated by signs of marine fossils across plains and mountains. And he theorized that if the first creatures on earth were of the sea, humanity must have evolved from such creatures.