俱舍論記 12.12

12.12

「如是已說至智者知夜減」者，此下第二明時量就中，一明其年量、二明諸劫量。此即明其年量。從夏至至冬至，夜增晝減。從冬至至夏至，晝增夜減。又解：時長名增，時短名減。若作此解，從秋分至春分夜增晝減，從春分至秋分晝增夜減，春分秋分晝夜停等。牟呼㗚多，此云須臾。一年之中總減六夜，此言減夜。影晝亦六減，顯一年中六月小也。分一年為三際，謂寒、熱、雨，各有四月。於此寒、熱、雨際十二月中，一月更半月已度，於餘半月應知減夜，如是乃至第六度一月更半月已度，於餘半月復減一夜。以此頌證，故減六夜。由此減夜，擬作潤月。論主所以不廣明諸曆數者，恐人耽著邪命自活。

"Having thus explained... up to: the wise know the nights decrease": Below this is the second part, which explains the measure of time. Within it, first the measure of years is explained, and second the measure of the various kalpas is explained. Here, it explains the measure of years. From the summer solstice to the winter solstice, the nights increase and the days decrease. From the winter solstice to the summer solstice, the days increase and the nights decrease. Another explanation: When the time is long, it is called 'increasing'; when the time is short, it is called 'decreasing'. If one adopts this explanation, from the autumnal equinox to the vernal equinox, the nights increase and the days decrease; from the vernal equinox to the autumnal equinox, the days increase and the nights decrease; at the vernal and autumnal equinoxes, day and night are equal. Muhūrta is translated here as an instant (xūyú). In one year, altogether six nights are diminished; this is called 'decreasing nights'. The daytime shadows also decrease by six, showing that six months in a year are hollow months (short months of 29 days). A year is divided into three seasons: cold, hot, and rainy, each having four months. In these twelve months of the cold, hot, and rainy seasons, when one month and another half-month have passed, in the remaining half-month one should know that a night decreases; in this manner, up to the sixth time that one month and another half-month have passed, in the remaining half-month another night is decreased. Using this verse as evidence, six nights are therefore diminished. By means of these diminished nights, intercalary months are established. The reason why the author of the treatise does not broadly explain the various calendar calculations is for fear that people might indulge in wrong livelihood to sustain themselves.