The day is divided into eight parts: four praharas for the day, and four for the night. The first prahara of the day begins at sunrise, and the fourth prahara of the day ends at sunset. A second round of four praharas unfolds during the night, between sunset and sunrise.
The traditional system of praharas overlaps (but does not coincide) with the more precise traditional system of muhurtas, which is based on precise astronomical calculations.
Thus, the day can be regarded as divided into eight praharas (of three hours each) or thirty muhurtas (of 48 minutes each). In both systems, the day commences with sunrise. The timing of the two systems coincides only at sunrise and sunset (four praharas coincide with fifteen muhurtas at the twelve-hour, or 720-minute, point).
In the ancient Puranas we see the day divided into eight praharas: four for the day and four for the night. The concept still prevails today in India, particularly in connection with the performance of Indian classical music (see below).
The concept of prahar originated where the lengths of the day and night were based on actual, observable sunrise and sunset. The four praharas of the day start at sunrise, and the four praharas of the night at sunset. If the location is near the equator, where day and night are the same length year round, the praharas of the day and the praharas of the night will be of equal length (three hours each). In other regions, where the relative length of day and night varies according to the season, the praharas of the day will be longer or shorter than the praharas of the night.
Contemporary discussions of prahara often use 6:00 am (the time of sunrise at the equator and at the equinoxes) as a theoretical fixed point of reference for mapping out the praharas at three-hour intervals (6-9, 9-12, etc.). This scheme is a useful pedagogical tool and an efficient way of applying the concept of prahara in a technological "clock" culture. However, it's important to realize that this rigid schema most likely does not capture the original application of prahara. In a traditional, non-technological culture, the length of day and night are based on observable sunrise and sunset. The day, which starts at sunrise and ends at sunset, is divided into four praharas of equal length; and, the night, which starts at sunset and ends at sunrise, is also divided into four equal watches. During the summer, when the days are longer than the nights, the praharas of the day will be longer than the praharas of the night, and vice versa during the winter.
The question of how to handle the praharas when days and nights are unequal in length is critical for timing the performance of ragas, since each raga is ideally performed during a certain prahara.
Indian classical music
Some ragas of Indian classical music are prescribed to be performed at a particular prahara to maximize their aesthetic effects (see samay). Perhaps the earliest mention of the relation between raga and time is Narada's Sangita Makaranda, written sometime between the 7th and 11th century, which warns musicians against playing ragas at the incorrect time of day. Pandit V.N. Bhatkhande (1860-1936), who formulated the modern system of Indian musical thāt, states that the correct time (or prahara) to play a raga has a relation to its thāt, or scale.
Modern etymology and usage
The word commonly used in India, Pakistan, Nepal is pahar (Hindi/Nepali पहर, Urduپہر), more commonly pronounced paher or peher and in West Bengal and Bangladesh is prohor (Bengali প্রহর). In Hindi and Urdu the word for "afternoon" is dopahar (= two prahars). In Bengali the corresponding word is dwi-prohor or more commonly dupur.
- Monier-Williams Sanskrit-English Dictionary, sv. "prahara."
- Bhagavata Purana (also known as Srimad Bhagavatam) 3.11.10
- Indic astronomical calculations identify the brahma-muhurta as the penultimate muhurta before dawn (in other words, the first of two muhurtas, or periods of 48 minutes, before dawn). If sunrise is at 6 am, the brahma-muhurta starts 96 minutes earlier, at 4:24 am. (The traditional calculations are available through GCal, computer software developed by the ISKCON GBC for the purposes of calculating the Vaishnava calendar, now available online and as iTunes app). See also Āgama-kosha, vol 4, by Saligrama Krishna, Ramachandra Rao, Rama R. Rao, Kalpatharu Research Academy, 1991. Other secondary sources speak of the brahma-muhurta as the antepenultimate muhurta before dawn (in other words, the first of three muhurtas before dawn). Assuming a 6 am sunrise, this would place the start of the brahma-muhurta at 3:36 am; see Gaya Charan Tripathi, "Communication with God: The Daily Puja Ceremony in the Jagannatha Temple" and Times of India. Yet other sources conflate the two accounts: they claim that the "brahma-muhurta" begins two muhurtas before dawn (i.e., 4:24), but say that it begins at 3:36 am (which would be three muhurtas before dawn); see the ISKCON program for morning sadhana. The precession of the equinoxes may complicate things yet further; see e.g. the discussion of Muhurta: yearly calibration.
- Some scholars correctly infer that in seasons (and regions) where days and nights are unequal in length, the praharas expand and contract in length. See Duncan Forbes' early comment on the pahar (= prahar) in Northern India: "The first pahar of the day began at sunrise, and of the night at sunset; and since the time from sunrise to noon made exactly two pahars, it follows that in the north of India the pahar must have varied from three and a-half hours about the summer solstice, to two and a-half in winter, the pahars of the night varying inversely." (Duncan Forbes, LL.D, transl. Bāgh O Bahār; or Tales of the Four Derwishes, by Mīr Amman of Dihli. London: W. H. Allen & Co. 1882, (p. 23, note 1). What we are encountering here is a difference between modern cultures that rely on clock time, and traditional cultures where the length of a day is observed in the sky, from sunset to sundown.
- Walter Kaufmann, The Ragas of North India, Calcutta: Oxford (1968)
- For Bhatkande's assignation of ragas to praharas, see Anthony Peter Westbrook, "Testing the Time Theory," Hinduism Today, February 2000. But note, contrary to Westbrook's assertion, that the concept of praharas existed long before Bhatkande made use of them in the 19th century; see, for example, the numerous references in the 16th century scripture Caitanya Caritamrta.
- Henry M. Hoenigswald, Spoken Hindustani, vol. 2, p. 403. Henry Holt (1945)