House Cusp

Definition

A house cusp is a marker degree tied to a house. Whether it starts the house or is just a point of strength inside it depends on the house system. In quadrant systems — Placidus, Koch, Regiomontanus, Alchabitius, Campanus — cusps come from dividing arcs of the sky into three (the day arc, prime vertical, or celestial equator) and mark house boundaries. In Equal House they mark boundaries at exact 30° steps from the Ascendant. In Whole Sign houses the sign boundary is the house boundary, and the Ascendant degree within a sign is a "point of intensity," not a start.

In Tradition

In Hellenistic and traditional astrology the cusp — from the Latin cuspis, "point" — was the place of strongest expression inside a house, not its arithmetic edge. Robert Hand documents that classic Equal House and medieval quadrant authorities set the cusp roughly five degrees into the house, and only in some modern Western reckonings did "cusp" come to mean strictly the beginning. In modern Western quadrant systems the cusp is read as both — the boundary and the peak of the house’s effect at once.

In Practice

You first choose a house system that fits the tradition you are working in — Hellenistic, Vedic, or modern Western — then read the sign on each cusp as the topical color of that house and that sign’s ruler as the house ruler. Many modern Western writers apply a "five-degree rule," treating a planet within about 5° of the late side of a cusp as already working in the next house. In Whole Sign practice the sign boundary is the house boundary, so cusp-orb questions never come up; the Ascendant degree within each sign is the sensitive point instead. In Hindu astrology the bhāva-madhya — the mid-house — is the strongest point. Cusps fall on the four angles in quadrant and Equal systems, but in Whole Sign houses they float relative to the sign boundaries.

Historical Origin

The Latin cuspis — "point," the tip of a spear — carries the original sense of "point" rather than "boundary." Hand cites this etymology and points to Hellenistic and medieval authorities, Firmicus Maternus among them, who treat the cusp as a point of intensity inside a house. Quadrant cusp-division was developed in the Arabic-medieval period (Alchabitius) and the late-medieval Latin period (Regiomontanus, Placidus, Campanus); Walter Koch’s post-WWII Birthplace System and the 20th-century British Equal House revival added the modern variants.

Etymology

Origin: Latin. Meaning: From Latin cuspis, "point" or "tip of a spear." Applied to the sharp dividing point between one house and the next..

Further Reading

  • Robert Hand, Whole Sign Houses: The Oldest House System
  • Deborah Houlding, The Houses: Temples of the Sky
  • James H. Holden, A History of Horoscopic Astrology