Placidian House System
Placidian House System(religion, spiritualism, and occult)
It is easy for a person looking at an astrological chart for the first time to make the incorrect assumption that the 12 “pie pieces” are the 12 signs of the zodiac. These lines indicate the house divisions (sign divisions are usually not represented), which can begin or end at different places in different signs. Astrologers disagree about how to draw the houses, although most agree that the first house should begin on the eastern horizon and the seventh house (180° away) should begin on the western horizon. Also, the great majority of systems begin the tenth house at the degree of the zodiac that is highest in the heavens and the fourth house at exactly 180° from the cusp of the tenth house.
The Placidian house system was developed by a 17th-century Italian monk and professor of mathematics named Placidus de Tito. In this system, the house cusps between the ascendant and the midheaven are obtained by trisecting the time it takes a degree of the zodiac to rise from the eastern horizon to the midheaven. Owing to the widespread availability of Placidian tables of houses, this was the most popular house system in the early 20 th century, and it still enjoys widespread use.