俱舍論疏 12.19

12.19

論「此晝夜至知夜減」，「有時增」者，晝夜總三十牟呼栗多，此云須臾。夜增時十八，晝有十二，即是此方冬至也。晝增，此方夏至也。「有時等」，當春、秋分也。「六月減夜」者，言夜兼晝。十二月中六月減夜，即是此方六月小盡也。引頌證。「寒熱雨際中」者，牒三際也。「一月半已度」者，謂雨月減一日，至第二月半已度，是第二月後半末缺一日，即是此方雨月減一日。「於所餘半月」，即是第二月後半月，此方亦有併小、併大及潤月等，略而不論。

On the Śāstra's words, "These days and nights [...] know that the nights decrease": "Sometimes increasing": day and night total thirty muhūrtas, which here are called moments (xuyu). When the night increases it has eighteen, and the day has twelve, which is the winter solstice in this land. When the day increases, it is the summer solstice in this land. "Sometimes equal" corresponds to the spring and autumn equinoxes. "Six months have decreasing nights": this refers to the night including the day. Among the twelve months, six months have decreasing nights, which is the six short months in this land. Citing the verse as proof: "Among the cold, hot, and rainy seasons" reiterates the three seasons. "When a month and a half have passed" means that in the rainy months one day is subtracted; when reaching a month and a half having passed, it is the end of the second half of the second month lacking one day, which is one day subtracted in the rainy months in this land. "In the remaining half-month" is the latter half of the second month; in this land there are also consecutive short months, consecutive long months, intercalary months, and so forth, which are omitted without discussion.