Thirty-Degree Profection (Intihā' bi-l-Thalāthīn)
Definition
The thirty-degree profection is ʿUmar al-Ṭabarī's distinctive Persian timing method, in which a chosen point is advanced not one whole sign per year but in thirty-degree increments, each span read as a compacted year. Within that span the astrologer measures the degree-distance from the profected point to the next benefic or malefic degree and converts it into days, so the technique fixes not only which year a matter falls in but the day it begins. It differs from the sign-by-sign profection used in the Hellenistic tradition and by Masha'allah, and applies to any sensitive point.
In Tradition
ʿUmar treats the thirty-degree span as a year in miniature: every two and a half degrees stands for about a month, and the degree-distance to the next benefic or malefic point converts into days from the year's start, telling when the indicated condition arrives. A malefic degree reached signifies duress and an evil turn; a benefic degree, bounty and increase. The method is the middle tier of ʿUmar's threefold timing, between the yearly direction in the nativity and the daily direction in the solar revolution.
In Practice
Choose the point you want to time — the Ascendant, the Lot of the Father, the Lot of the Mother, or any sensitive degree — and profect it forward in thirty-degree steps, one step for each year of life, treating the current thirty-degree span as that year compacted. Within the span, count the degrees from the profected point to the next benefic or malefic degree, then multiply that count by roughly twelve and a sixth days per degree, the figure ʿUmar derives from dividing the year's days across the thirty degrees, to get the number of days from the start of the year when the condition begins. Read a malefic degree reached as marking duress and an evil stretch in the native's affairs, and a benefic degree reached as marking bounty and increase. Use this thirty-degree count as ʿUmar's 'greater condition,' set between the general yearly direction of the nativity and the lesser daily direction of the solar revolution, so the three tiers together localize the timing.
Historical Origin
The method is set out in ʿUmar al-Ṭabarī's Three Books on Nativities (Book II, Ch II.4), preserved in Benjamin N. Dykes's translation in Persian Nativities (2010). Dykes flags it as ʿUmar's distinctive departure from the whole-sign-per-year profection that Masha'allah uses in the Book of Aristotle, with the degree-based reckoning and the roughly twelve-and-one-sixth days-per-degree subdivision marking the Persian character of the technique.