Aristotle didn't believe the ancient Greek theory of atoms being of different sizes, regular geometric shapes and being in constant motion. He didn't think atoms could be in constant motion in an empty space. He developed the theroy that all matter consisted of the four elements: Earth, Air, Water and Fire. He also made four different qualities qualities: dryness, hotness, coldness, and moistness. Fire was dry and hot, water was moist and cold, etc. (please refer to the chart). Each of these elements move naturally in a line to their "proper place," where it will be at rest. Aristotle's theory also had two forces: conflict and harmony. Conflict was thought to cause bad things, and harmony cauesed good things. Aristotle also believed that the heavens were made of a fifth, superior element named aither. Aristotle's theory was used for almost 2000 years, until after the scientific revolution, when other theories were discovered.