The Ionian philosophers were the first to break away from the mythological traditions surrounding the principles of Egyptian and Asiatic science. Thales of Miletus about the year 580 B. C. taught that there is an essence, force, or soul in all things. This universal principle of activity is superhuman. Seeking to find of what the world is made, he arrived at the idea that water, or moisture, is the basic element. All matter, he said, is water in various forms and combinations. Here we see scientific knowledge sought with a definite aim and with unity of purpose. None of the earlier peoples had ever attempted to approach knowledge in this logical and fruitful manner. When the learned Babylonians were asked what the earth was they simply said: "When the world was created, Marduk, the sun god, took Tiamat, or Chaos, and divided her. The sky was formed above and the earth below." And the Egyptians answered the question in a similar way by saying: "When the world was created, Shu tore the goddess Nuit from the arms of Keb, and now she hangs above him and he is the earth." It was this kind of statement that Thales cast aside. He sought for more concrete definitions. Customary beliefs were not acceptable to him; his knowledge must be based on reason. Here we see the dawn of a new scientific spirit and the beginning of a new method of investigating knowledge. The world was introduced to a new field of intellectual activities. The theory of Thales was studied by other Greek philosophers. But Anaximander, a friend of Thales, rejected it, and in its place suggested that there is one eternal, indestructible substance which constitutes the basis of matter. This was not water but an infinite eternal motion. Water is subjected to extremes of temperature. Under such conditions nothing could have been stable enough to constitute matter. A primary substance must be free from warring or antagonistic elements. The world arose, said Anaximander, through the evolution of a substance subjected to temperature changes which developed from the eternal, boundless, basic element. A sphere of flame arose from this, as from an explosion, and assumed a rounded form with concentric divisions. As these rings became detached, the sun, moon, stars, and other heavenly bodies and the earth were formed. Aristotle tells us that, according to Anaximander's theory, the terrestrial region was at first moist; and, as the moisture was dried up by the sun, the portion that was evaporated produced the winds and the turnings of the sun and moon, the remaining portion becoming the sea. In time the sea, Anaximander held, would dry up. The heat, or fire, of the world would burn the whole of the cold moist element. Then the world would become a mixture of heat and cold like the boundless, primary element surrounding it, and by which it would be absorbed.