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Ancient [[Greek]] scholars, such as [[Democritus]] and [[Aristotle]], thought of the material [[universe]] as being composed four different [[elements]]--[[earth]], [[air]], [[fire]], and [[water]].  Motion and interactions between objects were explained by the concept of a "natural state" for each element.  Bodies tended to move towards their natural state, and remained motionless when they attained it.  For example, a rock fell to the ground after being tossed in the air because it was composed mostly of earth; as such, it moved toward its natural state at the center of the Earth as much as it was able.  The Greeks also made advances in [[astronomy]]; [[Ptolemy]] developed a geocentric (Earth-centered) model of the solar system.

Ancient [[Greek]] scholars, such as [[Democritus]] and [[Aristotle]], thought of the material [[universe]] as being composed four different [[elements]]--[[earth]], [[air]], [[fire]], and [[water]].  Motion and interactions between objects were explained by the concept of a "natural state" for each element.  Bodies tended to move towards their natural state, and remained motionless when they attained it.  For example, a rock fell to the ground after being tossed in the air because it was composed mostly of earth; as such, it moved toward its natural state at the center of the Earth as much as it was able.  The Greeks also made advances in [[astronomy]]; [[Ptolemy]] developed a geocentric (Earth-centered) model of the solar system.

The ideas of the Greeks formed a [[paradigm]] that lasted for over 1500 years, making it one of the most successful scientific theories ever in terms of length of time spent as the dominant viewpoint.

The ideas of the Greeks formed a [[paradigm]] that lasted for over 1000 years, making it one of the most successful scientific theories ever in terms of length of time spent as the dominant viewpoint.

===The Scientific Revolution===

===The Scientific Revolution===