Horary — the question chart
Hellenistic katarchic practice through the Arabic tradition to William Lilly's Christian Astrology (1647)
Casting a chart for the moment a question is asked descends from Dorotheus's inceptional astrology, was developed by Arabic astrologers (Masha'allah, Sahl ibn Bishr, Bonatti), and reached its most influential English form in William Lilly's Christian Astrology (1647). Lilly's 'considerations before judgment' — checks on whether a chart is fit to read — are the heart of the method; he numbers none of them, and the two published enumerations both count about twelve.
What it measures
An ordinary chart for the instant and place of the question, read by traditional rulership: the Ascendant's ruler signifies the querent, the ruler of the relevant house signifies the matter, and the Moon co-signifies and shows the flow of events through the aspects it will complete before leaving its sign.
Where practitioners disagree
- When is the Moon void of course?
When it completes no further Ptolemaic aspect to a classical planet before changing sign (modern) — or Lilly's version with an exception for benefic-ruled signs — or an older fixed 30° span
The definitions place the void window differently; ours is the same one the electional finder uses.
This engine: No remaining Ptolemaic perfection to Sun–Saturn before the Moon's next ingress.
Still open
Lilly presents some considerations more firmly than others — the Via Combusta he offers only 'as some say' — so which are strict rules and which are cautions is itself a matter of judgment.
Sources
- William Lilly, Christian Astrology (1647)
- Guido Bonatti (trans. H. Coley), Anima Astrologiae (1676)