Sūta said: The night contains fifteen such muhūrtas and the day another fifteen muhūrtas. A (lunar) month according to human reckoning constitutes the night and day of the pitṛs. Divided further, the dark half constitutes the day and the bright half constitutes their night when they go to sleep. Thirty human months make one month of the Pitṛs. The period of three hundred and sixty months calculated according to human reckoning makes one year of the Pitṛs.