Direction of the Planet (Jihat al-Kawkab)
Definition
The direction of the planet is the prognostic rule, in the Arabic-Persian reception of Dorotheus, by which a significator's cardinal quadrant in the chart and its phase relative to the Sun tell you when in life a chronic illness will show itself. The Arabic nāḥiyat al-kawkab distinguishes the four quadrants — east, south, north, west — and pairs them with whether the significator is a morning star, rising before the Sun, or an evening star, setting after it. From these two readings the astrologer fixes both the life-stage of the affliction and whether it arrives early or late.
In Tradition
In this branch of natal medical judgment the timing of a chronic illness is localized, not just predicted: the quadrant the significator occupies assigns it to a stage of life — the eastern quadrant to the first half, the southern to the middle, the northern to adulthood — while the planet's morning-star or evening-star phase grades whether the trouble appears early, the more unfortunate verdict, or later, when it can be treated preventatively. Sahl and Theophilus of Edessa preserve the same Dorothean rule.
In Practice
Once you have identified the significator of the chronic illness, fix two things about it. First, find its quadrant in the chart: an eastern placement throws the affliction to the first half of life, a southern placement to the middle years, a northern placement to adulthood. Second, judge its phase against the Sun — is it a morning star, visible in the east before sunrise, or an evening star, visible in the west after sunset? A morning-star significator is read as bringing the illness earlier, which is the harder verdict; an evening-star one brings it later, when it may be caught and managed in childhood. Combine the two readings so that the quadrant gives the life-stage and the phase grades the early-versus-late onset, then weigh the result against the rest of the bodily-health testimony rather than pronouncing from this rule alone.
Historical Origin
The rule is given in Dorotheus of Sidon's Carmen Astrologicum (Book IV Ch 2), preserved through the Pahlavi-Arabic recension of ʿUmar al-Ṭabarī and in Benjamin Dykes's English translation. Dykes cross-references Sahl ibn Bishr's book on nativities (Ch 6.5) and Theophilus of Edessa's Cosmic Inceptions (Ch 4) as Arabic-tradition parallels carrying the same quadrant-and-phase timing of chronic illness.