Geocentricity might well be egocentricity - the phenomenon of retrograde motion is based on our Earth-centered view of the solar system, but the movement and cycles of retrograde planets are based entirely on the apparent motion of the Sun through the zodiac. Sullivan organizes and explains retrograde motion from a systems-viewpoint-the system of the Sun and planets-and interprets retrograde planets natally, by progression, and in transit. Sullivan has interpreted these movements in a way that is immediately apparent and useful to both novice and professional astrologers, and provides both psychological and mundane interpretations of retrograde planets.