Foundations of Astrology: Placidus

Placidus is one of the most widely used house systems in modern Western astrology. Developed in the 17th century by Italian monk and mathematician Placidus de Titis, this system divides the astrological chart into twelve unequal houses based on time rather than space. Specifically, it calculates how long it takes a degree of the zodiac to rise from the horizon to the Midheaven, producing house cusps that vary in size depending on the latitude of birth. This results in a chart that closely reflects the diurnal motion of the sky—the actual arc planets travel over the course of the day. What makes Placidus significant is its emphasis on the passage of time as a symbolic framework. It mirrors the natural rhythm of how life unfolds moment by moment, making it especially useful in psychological and counseling astrology. The unequal house sizes can highlight where life feels concentrated or sparse, adding nuance to areas such as identity (1st house), relationships (7th), or vocation (10th). While critics note its distortion at high latitudes, many astrologers value Placidus for its intuitive connection to lived experience. Spiritually and psychologically, Placidus can be seen as a lens through which consciousness encounters time and growth. Its time-based structure reminds us that development doesn't occur in equal measure across all areas of life. Some parts of the psyche may demand more focus, effort, or reflection than others. In this sense, Placidus supports a dynamic and deeply personal understanding of the natal chart—one that honors the unfolding journey of becoming.