Great Conjunctions

Definition

Great conjunctions are the meetings of Jupiter and Saturn, which line up about every 19.85 years. Medieval Arabic astrologers made them the cornerstone of mundane astrology — the branch that reads events for whole peoples rather than for one person. Successive conjunctions keep landing in signs of the same element for roughly 200 years, then shift to the next element, a move called a "mutation." Over about 800 to 960 years they pass through all four elemental groups, a "great cycle" used to mark off long historical eras.

In Tradition

Medieval Arabic-Persian astrology — set down in Masha'allah's De Revolutione Ch. 22 and worked out fully by Abu Ma'shar's Book on the Great Conjunctions — sorts mundane prediction into three nested tiers. The "great" conjunction (Saturn and Jupiter, roughly every 20 years) marks shifts in religions and dynasties; the "middle" conjunction (Saturn and Mars, on Dykes's reading) marks wars; the "lesser" marks the year's political shifts, set off by profection. Bonatti's Liber Astronomiae carries the doctrine into the medieval Latin world.

In Practice

A mundane astrologer follows each Jupiter-Saturn conjunction and casts a chart for the exact moment it perfects, set for the place that matters — usually a national capital. You read that chart for the element the conjunction falls in (cycling fire → earth → air → water in roughly 200-year blocks), the sign and degree of the conjunction, how angular Jupiter and Saturn are, and the planets that rule the conjunction-sign. A conjunction that marks a shift of element — a "mutation conjunction" — is read as a turning point of the largest kind: a change of religion, of dynasty, or of world-historical era. You then track that founding chart through later Aries-ingress charts and through profections of the conjunction itself, building a layered system of prediction used in medieval Islamic court astrology and carried on through Bonatti and Lilly into the modern revival.

Historical Origin

The Saturn-Jupiter conjunction-cycle doctrine is preserved in Masha'allah's De Revolutione (8th-9th century, transmitted into Latin by Hugo of Santalla and others) and treated systematically in Abu Ma'shar's Kitāb al-qirānāt — On the Great Conjunctions (9th century, Arabic, public domain). Bonatti's Liber Astronomiae Vol VIII tractate II and Vol XI part III give the medieval Latin reception. Benjamin Dykes's modern English editions (Persian Nativities, Works of Sahl & Masha'allah, and the Bonatti volumes) have made the doctrine accessible since the 2000s.

Definition

In Tradition

In Practice

Historical Origin

Further Reading