Siddha

Siddha is the twenty-first nityayoga, and its name means accomplished, perfected, or one who has attained. It is one of the auspicious yogas, favourable for undertakings aimed at success and for spiritual practice, the word siddha in the wider tradition names an accomplished adept. Reckoned like the others from the summed longitude of Sun and Moon divided into twenty-seven parts, it advances through the month. In the panchanga it lends its quality of attainment to the reckoning of an auspicious moment, one of the five daily limbs weighed for muhurta. These are the conventions of the calendar tradition, in which each of the twenty-seven yogas carries a settled character; Siddha falls among the benefic set. The astronomical basis is the combined motion of Sun and Moon.

Siddha, an adjective built from the same root as Siddhi, the sixteenth yoga, names in the wider tradition an accomplished spiritual adept, one who has attained the supernatural powers and liberated state that practice is said to confer, and Siddha in this sense is also the name of an entire medical and alchemical tradition, Siddha medicine, practised principally in Tamil Nadu and associated with legendary adept-physicians distinct from the more widespread Ayurvedic system. The nityayoga's own use of the word is the general calendrical sense of favourable attainment rather than a direct reference to either the yogic adept or the medical tradition, though all three uses draw on the same underlying sense of a state successfully reached or perfected.

A yoga is arrived at by addition, which sets it apart from every other reckoning in the almanac. Where the tithi measures the Moon's separation FROM the Sun, the yoga measures the two longitudes ADDED together, and cuts the resulting circle into twenty seven equal arcs of thirteen degrees twenty minutes. Siddha is the arc from 266 degrees 40 minutes to 280 degrees 00 minutes of that sum. The sum climbs at roughly fourteen degrees ten minutes a day, so a yoga runs about twenty two and a half hours on average, a little shorter than a tithi, and like a tithi it can be skipped between two sunrises or carried across two of them.

The twenty seven arcs are the same width as the twenty seven nakshatras, and Siddha is the twenty first arc of the grid in both schemes, which is why the two are often tabulated side by side. They are not the same thing and share nothing but their arithmetic: a nakshatra is a segment of the sky the Moon is physically standing in, while a yoga is a number derived from two positions and belongs to no part of the sky at all. Reading a yoga as a star group is the commonest confusion the term invites, and the shared name of the twenty first position, Uttara Ashadha, is where it usually starts.

Siddha sits among the eighteen yogas classed as favourable. That count matters more than it looks: with eighteen of twenty seven benign, the yoga is a weak filter on its own, and the classical muhurta writers use it as a tie breaker between candidate times rather than as a reason to reject one. A day is not made auspicious by its yoga alone.