I use Morinus for traditional primary directions - ''Placidus'' semiarc, zodiacal, without latitude, with aspects of ''promissors to significators'', the key doesn't matter much, but I use the so-called Ptolemaic.
Martin Gansten has an excellent introduction on the subject. I haven't read his full book that goes through many authors and methods though. -
http://www.martingansten.com/pdf/PrimaryDirectionsChapter.pdf
If it is possible anyway....
Or just use the 4min direction = 1yr of lifespan rule? So if I was born at 10:00 so 30 years will be 12:00?
1 year of lifespan = 1 degree of RA = 4 equinoctial/modern (not local) minutes (with the so-called ''Ptolemaic'' key)
You can see the direction of the Ascendant and the Midheaven (and planets in exact conjunction with them) by adding that amount of time, and proportionally for the planets in between the angles (if you keep the original distances in mind).
What are the significators? Angles and/or house cusps? Can the IC be a significator?
Can Part of Fortune be a promissor? Or only planetary bodies?
Ptolemy and some medieval astrologers allowed only five significators - the Ascendant for body and travel, the Sun for dignity and marriage for women, the Moon for mind and marriage for men, the Lot of Fortune for wealth and property, and the Midheaven for actions, children and friendship. I believe Ptolemy and Cardanus were right that these broad significators are enough to cover all individual aspects of life with the necessary amount of differentiation (some Hellenistic astrologers directed a single planet/predominator for all events in general).
Lilly described 10 significators with 5 of them as necessary, while also specifying accidental rulership (Ptolemy doesn't use houses much):
First, the Horoscope, or Ascendant, we direct in every Nativity, for that it signifieth the Life and Body of man, his Complexion, the Affections and Manners of his Body and Minde […]
Secondly, we direct the Moon in regard she signifies the Complexion of the Body, and its Intentions, the Natives Journeys, Peregrinations, his Matrimony, the state of his Wife, Women and neer Kinsfolkes.
Thirdly, the Directions of the Sun are made especially, concerning the Native’s good or bad health, his Honour or Preferment publick or private, the favour of great Persons, the state of his Father, and his Estimation.
Fourthly, medium-cæli we direct for Honour, Offices in the Common- wealth, the friendship of Nobility, Kings and Magistrates, for the Magistery, Trade or Profession of the Native, for his Mother.
Fiftly, the Part of Fortune being directed to the good or evill aspects of the Fortunes or Infortunes shewes the encrease or diminution of Riches […]
Sixtly, you may direct Saturn to signifie your Ancestors, Inheritances, Buildings, Possessions, the Fruits of the earth; so also, Fears, Jealousies, Mistrusts, &c. according as Saturn is well or ill affected.
Seventhly, we direct Jupiter for Glory, Renown, Riches, Children, Religion, Sobriety, &c.
Eightly, Mars is directed for Animosity, Victory, War, Law-suits, and he shewes the estate of Brethren.
Ninthly, Venus is directed for Matrimony, Love, Pleasure, rich Ornaments, Maids, Women, &c.
Tenthly, we direct Mercury for the Wit, Understanding, Trade, Industry, Negotiations, Journeys, our lesser Brethren, for Schollership, History, &c.
The Planets do signifie these things properly of themselves in Directions, in what Nativity soever they be, or in what part of Heaven; but accidentally, they have signification according to the nature of the Houses they are in, and are Lords of; by considering whereof, you shall finde the true intention of what is signified by the Direction.
7. Lilly 1659:653 f. A note in the margin reads: ‘It’s not usual to direct but the former five.’ quoted from
http://www.martingansten.com/pdf/PrimaryDirectionsChapter.pdf
Morinus allowed 20 significators, the aforementioned + the 10 other house ''cusps''. He criticizes some authorities for using only 5.
Here is why I believe the 5 are enough:
Sixtly, you may direct Saturn to signifie your Ancestors, Inheritances, Buildings, Possessions, the Fruits of the earth; so also, Fears, Jealousies, Mistrusts, &c. according as Saturn is well or ill affected. - the first part overlaps with the Lot of Fortune and the second with maleficent chronocratorship over the Midheaven.
Seventhly, we direct Jupiter for Glory, Renown, Riches, Children, Religion, Sobriety, &c. - this overlaps with the Sun, the Lot, and the Midheaven.
Eightly, Mars is directed for Animosity, Victory, War, Law-suits, and he shewes the estate of Brethren. - this overlaps with the Midheaven, but what is most concerning to me here, is that war does not apply to many non-military nativities, indicating superfluousness, for in military nativities, one can investigate the Midheaven as he would do with any career.
Ninthly, Venus is directed for Matrimony, Love, Pleasure, rich Ornaments, Maids, Women, &c. - this overlaps with the Moon, Lot and Midheaven.
Tenthly, we direct Mercury for the Wit, Understanding, Trade, Industry, Negotiations, Journeys, our lesser Brethren, for Schollership, History, &c. - same thing as with Mars, it does not apply to every nativity, which is probably why some astrologers omitted it, and in case where they are related (when Mercury controls the Sun and the Midheaven at the nativity for example), they overlap with the function of the primary significators (for example career and the Midheaven), that is accidentally modified to the subject (for example property with Saturn, banking with Jupiter, military with Mars, arts with Venus, trade with Mercury etc.) at the nativity.
Every planet (Sun, Moon, Saturn, Jupiter, Mars, Venus or Mercury) becomes general chronocrator over the significator with conjunction, sextile, square, trine or opposition until the next planet with aspect. This is how Ptolemy used primary directions (along with the terms) as chronocratorship, not for single events or hits as it is fashionable in modern astrology. Lilly and Morinus also directed fixed stars to them. Some used latitude to change the interpretation of conjunctions and sometimes oppositions. There are of course many differences in interpretation from author to author. Predictive techniques have to be used in accordance with the foundations of the natal chart, cookbooks are impossible here.