Hellenistic astrology is the oldest known tradition of astrology, founded in the hellenistic period in Greece/Mesopotamia.
In their time, Neptune, Uranus and Pluto were not yet discovered. Only 5 planets + 2 luminaries (i.e. the Sun and the Moon) were used.
According to Valens, “Each star is the ruler of its own ‘element’ in the universe…” (Anthologies, Book I):
The moon becomes the ruler of foresight, the sun the ruler of light, Saturn the ruler of ignorance and necessity, Jupiter the ruler of rank, crowns and zeal. Mars becomes the ruler of action and effort, Venus the ruler of love, desire, and beauty, Mercury the ruler of law, friendship, and trust.
The word ‘horoscope’ means ‘hour decider’ which is your Ascendent. Knowing the exact time of your birth, you can pinpoint where your Ascendent is in your chart.
To divide your natal chart wheel into 12, ‘whole signs’ system is used: 1st house (or place) does not start at the degree of your Ascendent, but it starts from 0 degree of the sign it falls. For example, if your Ascendent is Aries at 18 degrees, your 1st place is Aries (from 0 to 30 degrees), 2nd place Taurus, and so forth. Your chart looks simpler because of this (and makes more sense to those who have converted from other methods).
What are the meanings of the 12 places? The 1st place is about you, while the rest is about events and situations in relation to other people in your life. It is easier to see them in pairs:
1st (Helm): physical life – 7th (Setting angle): opponent/spouse
2nd (Gate of Hades): livelihood – 8th (Inactive): death, inheritance
3rd (Goddess): short distance travel/local authorities – 9th (God): long distance/national
4th (Subterranean angle): parents, home – 10th (Culminating angle): career, action
5th (Good fortune): children – 11th (Good spirit): friends
6th (Bad fortune): health issues – 12th (Bad spirit): enemy within.
If we both have the sun in Taurus, but you have it in your 10th place, and I have it in my 5th, that makes our self expression quite different. Or if your Sun is in Aries and mine in Taurus, but we both have it in our 7th place, then there’s a common factor.
You know what 12 zodiacal signs are. Different planets rule different signs:
Moon rules Cancer
Sun rules Leo
Mercury rules Gemini (Day) and Virgo (Night)
Venus rules Taurus (N) and Libra (D)
Mars rules Aries (D) and Scorpio (N)
Jupiter rules Pisces (N) and Sagittarius (D)
Saturn rules Aquarius (D) and Capricorn (N)
Apart from the sun (Leo) and the moon (Cancer), each planet rules 2 signs of the zodiac, day or night, equally distributing their rulership across the sky.
If your Sun was in Gemini and Moon in Virgo, they would be united by a common thread: ruler Mercury.