Dhriti

Dhriti is the eighth nityayoga, and its name means steadiness, firmness, and resolve. It is classed among the auspicious yogas, favourable for undertakings that call for constancy and perseverance and for matters requiring a firm foundation. Reckoned from the summed longitude of Sun and Moon divided into twenty-seven parts, it advances as the lights draw apart. In the panchanga it lends its steadying quality to the reckoning of an auspicious moment, one of the five daily limbs consulted for muhurta. These are the conventions of the calendar tradition; the underlying reality is the combined motion of the two luminaries, whose summed longitude sweeps through the twenty-seven yogas over the course of a lunar month.

Dhriti, steadiness or firm resolve, is also used in classical Sanskrit ethical and dramatic theory as the name of a specific mental quality, the fortitude that allows a person to bear hardship or temptation without wavering, sometimes listed among the qualities an ideal hero or a disciplined practitioner is expected to cultivate. The yoga's association with constancy and perseverance draws on this established sense of the word rather than inventing a new meaning for astrological purposes, and dhriti in this ethical, non-astrological sense appears independently across a wide range of classical Sanskrit philosophical and literary texts, well outside any calendrical context.

Of the five limbs of the panchanga the yoga is the most purely arithmetical, and the only one a person standing outside at night could never read off the sky. 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. Dhriti is the arc from 93 degrees 20 minutes to 106 degrees 40 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 Dhriti is the eighth 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 eighth position, Pushya, is where it usually starts.

Dhriti 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.