Hyleg and alcocoden
Hyleg (the giver of life) and alcocoden (the giver of years) are the two appointed planets in a longevity reading. Ptolemy's procedure in Tetrabiblos III selects the hyleg from a candidate set (the Sun by day, the Moon by night, the Ascendant, the Lot of Fortune, and the syzygy preceding birth) by sect-conditional rules. The alcocoden is the planet that has the most dignity over the hyleg's degree.
Choosing the hyleg
Lilly tabulates Ptolemy's selection. Day chart: examine the Sun first; if it is in one of the five hylegiacal places (1st, 7th, 9th, 10th, or 11th house) and has dignity by domicile, exaltation, or triplicity in its degree, it is hyleg. If not, examine the Moon by the same test. If neither qualifies, take the Ascendant. Night chart: Moon first, then Sun, then the Lot of Fortune. The chart of conception (the lunation immediately before birth) supplies the Ascendant if no luminary qualifies.
Choosing the alcocoden
Once the hyleg is fixed, find the planet with the most dignity over the hyleg's degree (domicile 5, exaltation 4, triplicity 3, term 2, face 1). That is the alcocoden — the planet that 'gives years.' Each planet has a tradition of three different year-allotments: greatest, mean, and least. The alcocoden's condition (dignified, debilitated, aspected by malefics) selects which of the three to apply.
Reading the result
Classical longevity is not a death-date prediction. It is a structural reading of the life-vessel: where the hyleg is well-placed and the alcocoden is dignified, the body and life force have a sponsor; where both are debilitated and afflicted, the tradition reads structural fragility. Modern practitioners use the technique as an indicator of vitality and constitution, not a fortune-telling claim — and Netra surfaces it in that spirit.
How Netra uses it
The Hyleg panel walks Ptolemy's selection live: it shows the hyleg candidates, the qualifying tests each one passes or fails, and surfaces the chosen pair with the alcocoden's allotted years. The Sect panel and the Almuten calculator are upstream of this routine.
Illustrative natal chart — the technique above applies to any chart you compute in Netra.
Sources
- Claudius Ptolemy, Tetrabiblos, Book III (Ashmand, 1822)
- William Lilly, Christian Astrology (1647), Book III
- Vettius Valens, Anthology, Book III
See Sources for the full corpus and the public-domain policy.
Related
- Essential dignities — The five-fold table of planetary strength by zodiacal placement — domicile, exaltation, triplicity, term, and face.
- Sect — The diurnal–nocturnal split that determines which planets are in their preferred environment.
- Almuten — The planet with the most aggregate dignity at a given degree — the synthesis of essential dignity into a single ruler.
- Arabic parts (lots) — Derived points formed from the geometry between three chart positions — the Lot of Fortune is the canonical example.