In the 1940s, after studying the work of scholars who had translated the ancient Babylonian astronomical and astrological texts excavated from the Near and Middle East, Fagan realized that the Babylonians had used a sidereal zodiac—aligned to the stars—rather than a tropical zodiac—based on the seasons—later introduced by the Greeks. Fagan, a long time tropical astrologer, knew that this discovery would have profound implications for the modern day practice of astrology.