Pusio

POO-see-oh

Definition

Pusio is a medieval-Latin term, from the Bonatti-Alchabitius line of transmission, for a planet sitting in the sign directly opposite the one it rules — the seventh sign counted from its own. The condition lines up closely with what later Latin tradition settled on as detrimentum (detriment) and what Arabic sources call wabāl. Bonatti himself uses a related word, descensio, loosely, letting it cover both detriment (seventh from domicile) and fall (seventh from exaltation), and Hand's Project Hindsight footnote at Liber Astronomiae Vol III flags that the terms get tangled together.

In Tradition

In medieval Latin and Arabic-Persian astrology, a planet opposite the sign it rules counts as one of the recognized essential weaknesses, and scores against it in the dignity tally. Lilly's Christian Astrology I gives detriment a −5, the mirror of the +5 awarded for domicile. Bonatti's Liber Astronomiae Vol III keeps the seventh-from-domicile rule, though his Latin terms — pusio, descensio, detrimentum — are used inconsistently across the work, sometimes blurring detriment with fall (per Hand's p. 65 footnote in the Project Hindsight edition).

In Practice

When you weigh a planet's essential dignity — the strength it draws from where it sits — you first check domicile (the planet in its own ruled sign, +5), then run through the other four dignities (exaltation, triplicity, bound, face), and finally check the two essential weaknesses: detriment (the planet opposite its domicile, −5) and fall (the planet opposite its exaltation, −4). A planet in detriment — called pusio in Bonatti's loose Latin, or detrimentum in the tighter medieval convention — is read as poorly placed for expressing what it stands for: Mars in Libra cannot reach its martial drive cleanly, and Venus in Aries cannot express her relational and aesthetic side smoothly. Modern Western traditional practice (Lehman's Essential Dignities, Lilly's Christian Astrology) keeps the seventh-from-domicile detriment scoring as standard.

Historical Origin

The detriment-as-seventh-from-domicile doctrine is preserved in Ptolemy's Tetrabiblos (2nd-century-CE Greek, public domain) and set down in the medieval Latin reception through Bonatti's Liber Astronomiae Vol III-V (13th century, public domain) and Lilly's Christian Astrology I (1647, public domain). Bonatti's loose use of descensio for both detriment and fall is documented in Hand's footnote at p. 65 of the Project Hindsight Vol III edition.

Further Reading