Full context:   By the 4th century BC, Babylonian astronomy and its system of celestial omens influenced the culture of ancient Greece, as did the astronomy of Egypt by late 2nd century BC. This resulted, unlike the Mesopotamian tradition, in a strong focus on the birth chart of the individual and the creation of Horoscopic astrology, employing the use of the Ascendant (the rising degree of the ecliptic, at the time of birth), and of the twelve houses. Association of the astrological signs with Empedocles' four classical elements was another important development in the characterization of the twelve signs.