Final answer:
Ancient cultures believed the stars and planets symbolized the gods, influencing their understanding of events, including diseases. Natal astrology became mainstream with the Greeks and Ptolemy's work, linking celestial positions at birth to fate and personality. Despite a lack of scientific evidence, astrology persists in some practices today.
Step-by-step explanation:
People believed that disease could be diagnosed by consulting astrological charts because many ancient cultures viewed celestial bodies as representatives or symbols of the gods. This connection linked the study of the heavens directly to the understanding of divine will, especially regarding phenomena like weather, diseases, and accidents, which were all seen as expressions of the gods' contentment or displeasure. The Greeks popularized natal astrology by suggesting that the configuration of the heavens at birth influences an individual's personality and fate, an idea consolidated by Ptolemy in Tetrabiblos. Today, despite no scientific evidence supporting astrology's predictive power on personality or diagnosis, some people continue to consult astrology for guidance, with astrologers often providing therapeutic conversations.