“After the occupation by Alexander the Great in 332BC, Egypt came under Greek rule and influence, and it was in Alexandrian Egypt where horoscopic astrology first appeared. The endeavor to trace the horoscope of the individual from the position of the planets and stars at the time of birth represents the most significant contribution of the Greeks to astrology. This system can be labeled as “horoscopic astrology” because it employed the use of the ascendant, otherwise known as the horoskopos in Greek.
The system was carried to such a degree of perfection that later ages made but few additions of an essential character to the genethlialogy or drawing up of the individual horoscope by the Greek astrologers. Particularly important in the development of horoscopic astrology was the astrologer and astronomer Ptolemy , whose work, the Tetrabiblos laid the basis of the Western astrological tradition. Under the Greeks and Ptolemy in particular, the planets, Houses, and Signs of the zodiac were rationalized and their function set down in a way that has changed little to the present day. Ptolemy’s work on astronomy was the basis of Western teachings on the subject for the next 1,300 years.”