Dwadasamsa

Definition

The Dwadasamsa (D-12) is what you get when you cut a sign into twelve equal slices of 2 degrees 30 minutes each — one of the six Shadvarga, the six divisions Jyotish reads alongside the main chart. Each slice carries the name of a zodiac sign: the first is the sign itself, and the rest follow in zodiacal order, so the twelve parts of Mesha (Aries) run Mesha, Vrishabha, Mithuna, and on to Meena. Each slice keeps the same lord as the Rasi (sign) it is named for.

In Tradition

Across the classical and modern Jyotish sources gathered here, the Dwadasamsa is the divisional chart you turn to for the parents and ancestry. Raman follows Parasara in reading the D-12 for matters of the parents, and Cole likewise ties it to the parents and to ancestral karma. They agree on this broad significance, even as each adds its own further detail.

In Practice

Astrologers reach for the Dwadasamsa mostly on questions of parents and lineage. Raman, following Parasara, reads the D-12 for the parents, and in How to Judge a Horoscope he directs that ear defects and deafness — indicated by evil planets in the third house — be confirmed and refined here in particular. He also uses it for birth-time rectification: the Dwadasamsa rising when a question is asked fixes the sign Jupiter occupied at birth, counted from the Prasna Lagna (the sign rising at the question). Jataka Parijata adds two uses: the Dwadasamsa of the Lagna (rising sign) counts the trees on an estate — called Viyonijanma — and the Dwadasamsa the Moon sits in, with the fraction the Moon has travelled, predicts the Rasi (sign), the Nakshatra (lunar mansion), and a child's time of delivery. Cole takes the Sun and Moon as the karaka planets (significators) and the fourth and ninth houses as the karaka-bhavas, substituting a fixed karaka — Venus, or Mars — when both houses share one lord.

Historical Origin

The Dwadasamsa goes back to classical Sanskrit texts and is carried forward by modern authors. It appears in Varahamihira's Brihat Jataka (Ch.I Sl.6 and its Notes), where it is counted among the Shadvarga, and in Vaidyanatha Dikshita's Jataka Parijata (Adh.III). Modern treatments include Raman's Hindu Predictive Astrology and How to Judge a Horoscope, and Cole's Science of Light, which notes that the Romans called this division the dodecatemoria.

Further Reading

• Varahamihira, Brihat Jataka
• Vaidyanatha Dikshita, Jataka Parijata
• Raman, Hindu Predictive Astrology
• Raman, How to Judge a Horoscope, Vol.1
• Cole, Science of Light, Vol I