with Simplicius. Beginning with primitive Matter, (identical with air mingled with Mind), by a process of thickening and thinning, arose cold and warmth, or water and fire, the one passive, the other active. Archelaus deduced motion from the opposition of heat and cold, caused by the will of the material Mind. This opposition separated fire and water, and produced a slimy mass of earth. While the earth was hardening, the action of heat upon its moisture gave birth to animals, which at first were nourished by the mud from which they sprang, and gradually acquired the power of propagating their species. Humans also appear, at first in lower forms. All these animals were endowed with mind, but humans separated from the others, and established laws and societies. It was just from this point of his physical theory that he seems to have passed into ethical speculation, by the proposition, that right and wrong are "not by nature but by custom" ()—dogma possibly suggested to him by the contemporary Sophists. Of the other doctrines of Archelaus, he asserted that the Earth was flat, but that the surface must be depressed towards the centre; for if it were absolutely level, the sun would rise and set everywhere at the same time. He also said that the Sun was the largest of the stars. He accounted for speech by the motion of the air; for this, he seems to have adopted the views of Anaxagoras. Notes Sources — From Attribution External links Archelaus: Fragments 5th-century BC Greek people 5th-century BC philosophers Ancient Greek metaphysicians Metic philosophers in Classical Athens Philosophers of ancient Ionia Presocratic philosophers