Source: Astrology Weekly
Hellenistic astrology got its name from the region and period in which it was practiced - Hellenistic Egypt during the Hellenistic Period. It is believed that the practice of it began some time in the 3rd century (around the time of Alexander's conquest) until the 6th or 7th century CE, although the exact period is unknown. This type of astrology had a big influence on other types of astrology including Indian, Arabian, and European astrology.
It was during the time of Alexander the Great's conquest of the Persian Empire that so many different cultures came under the same rule and the same official language for the first time. Alexandria, Egypt was the center of all this multi-cultural activity. Among the thoughts and ideas that prospered from this blending of cultures was astrology. Astrologers like Berossus began doing horoscope interpretation. Yet some Hellenistic astrologers believe that it was Hermes Trismegistus, a mythical sage that was a combination of the Greek God Hermes and the Egyptian God Thoth, that created the horoscope system used during Hellenistic times and then handed the system down to Egyptian Pharaoh Nechepso and his priest Petosiris.Hellenistic astrology consists of three major subdivisions. The first subdivisions, Universal astrology, is used to predict events that will affect a large group of people, such as something weather related like a tsunami or a natural disaster such as an earthquake or disease epidemic. It can also include man made calamities such as war.
The second subdivision, Natal astrology, involves using an individual's birth time and date to create a birth chart. This will determine not only their personality traits, but also the paths they will take in life.
The final subdivision is Katarchic astrology. This uses electional astrology, which helps individuals know the best time to do something according to their chart. A person might use electional astrology to help them pick the perfect date for their wedding. Katarchic astrology will use event astrology as well, which helps people understand all the details of a particular event.
Many aspects of Hellenistic astrology are still used today in other branches of astrology. The concept of Houses, which set Hellenistic astrology apart of other types practiced at the same time, is still used today and that was developed during the time of Hellenistic astrology. Birth charts are also still used to tell a person's horoscope and life path. Hellenistic astrology also developed the concept of Lots. There are more than twelve lots, but the Lot of Fortune is one of the most important. It can be calculated as Ascendant + Moon - Sun.