What is the central idea of the Ptolemy selection? How does Ball develop this central idea?

The central idea of the Ptolemy section is that in ancient times, astronomy was based on a flawed theory. This theory stated that Earth was the center of the solar system and the sun and the other planets revolved around it. However, in this section, Ball also praises Ptolemy’s achievements from that era, which came from observations made without telescopes or other basic advances in technology that we take for granted today. Ball develops this section by discussing the limited technology and scientific understanding from Ptolemy’s time. He then discusses how Ptolemy used the belief systems of the time, such as circles being a symbol of perfection, that the world was round, and that the stars shifted across the sky. These beliefs allowed him to formulate his model of planetary motion, which claimed that the planets and sun circled Earth.