yāmāś catvāraś catvāro
martyānām ahanī ubhe
śuklaḥ kṛṣṇaś ca mānada
yāmāḥ—three hours; catvāraḥ—four; catvāraḥ—and four; martyānām—of the human beings; ahanī—duration of day; ubhe—both day and night; pakṣaḥ—fortnight; pañca-daśa—fifteen; ahāni—days; śuklaḥ—white; kṛṣṇaḥ—black; ca—also; mānada—measured.
It is calculated that there are four praharas, which are also called yāmas, in the day and four in the night of the human being. Similarly, fifteen days and nights are a fortnight, and there are two fortnights, white and black, in a month.
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