Amsayu

sanskrit: अंशायुर्दाय (Aṃśāyurdāya)

Definition

Amsayu, or Amsayurdaya, is a Jyotish method of longevity (Ayurdaya) that reads the life-span from the Navamsas — the ninth-part divisions, or amsas — that each planet and the Lagna (the rising sign) have passed through. Here the years a body gives correspond to how many Navamsas you count from Aries, so it is each planet's and the ascendant's divisional position, not a fixed per-planet allotment, that sets its share of years. Those shares are added, then put through prescribed increases and reductions to reach the final span.

In Tradition

The classical Jyotish texts that lay out the three Ayurdaya systems agree on when Amsayu applies: you use it when the Lagna (the ascendant) is the strongest of the Lagna, Sun and Moon. The Phaladeepika says it is reckoned on the predominance in strength of the Lagna, and the Uttara Kalamrita that it is taken as final when the Lagna outweighs both Sun and Moon; the Brihat Parasara Hora Sastra holds the same selection rule.

In Practice

A jyotishi reaches for Amsayu only once the strength test points to it: the Phaladeepika and Uttara Kalamrita choose it when the Lagna outweighs the Sun and Moon (Pindayurdaya goes by the Sun's strength, Naisargikayurdaya by the Moon's). To get each planet's and the Lagna's years, you turn its longitude into a Navamsa portion — but the texts differ on how. The Brihat Parasara Hora Sastra multiplies the longitude by 108 and reduces modulo 12; the Phaladeepika and Charak convert it to minutes and divide by 200; the Uttara Kalamrita counts constellations from Ashwini, divides by three, and works the navamsas out from Mesha. The sources then prescribe increases — for exaltation, retrogression, Vargottama and own divisions — and the standard reductions, with the Jataka Parijata and Brihat Jataka noting that the Krurodaya reduction is dropped here. Raman walks the method through a chart, arriving at 68 years 10 months against a death at 70.

Historical Origin

Amsayu is attested across the classical Sanskrit corpus. Varahamihira (in the Brihat Jataka) and Mantreswara (in the Phaladeepika) both ascribe it to the sage Satyacharya, and Varahamihira judges it the best of the three Ayurdaya systems. It also appears in the Brihat Parasara Hora Sastra (Ch.43), the Jataka Parijata of Vaidyanatha Dikshita (citing Sripathipaddhati), and the Uttara Kalamrita of Kalidasa. Modern authors, Charak and Raman among them, set out the same computation.

Definition

In Tradition

In Practice

Historical Origin

Further Reading