The early Greek philosopher Thales and his followers tried to achieve a rational understanding of the nature of the universe. A. In the Milesian School established by Thales. Teachers taught what they knew to their followers, who were then strongly encouraged to correct any errors in reasoning. B. Among early Greek philosophers, there was sharp disagreement even between teachers and students about the essential substance from which the world was made. C. Much of the written work of Anaximander and of Anaximenes has been lost, including a major work on the history of the universe by Anaximenes. D. Anaximander's work covered a broad range of issues that influenced later Greek thinkers, including the origin of life, the history of the universe, and the shape of both Earth and the sky. E. The ideas about astronomy held by members of the Milesian School continued to be widely accepted by scientists even after the Scientific Revolution in the seventeenth century. F. While Greek philosophers' theories about the world did not rely on appeals to supernatural forces, they also were not scientific, since they were not tested with experiments.