Within a matter of a few years, Anaximander understands that Earth floats in the sky and the sky continues beneath Earth; that rainwater comes from the evaporation of water on Earth; that the variety of substances in the world must be susceptible to being understood in terms of a single, unitary, and simple constituent, which he calls apeiron, the indistinct; that animals and plants evolve and adapt to changes in the environment, and that man must have evolved from other animals.
