Part 2.2.2 - Units of time

[Full title: Classification of Jyotiḥśāstra (1): Gaṇita of the Veda and the Vedāṅga Period (1): Units of time]

Gaṇita of the Veda and the Vedāṅga Period is primarily a record of the natural divisions of time based on the motion of the Sun and the Moon. Ṛtus (seasons), a natural division of time and on which depended the extent of the Vedic year, were discovered to be five or six. (Mai, Saṃ. I. 7.3, Atharvaveda VI. 55.2). Vasanta is the first of the Ṛtus^[1] and marks the beginning of the year a Ṛtu being a solar division of time, the year is naturally solar with 12 months, 360 days or of 720 days and nights together.^[2] The six seasons were distributed amongst the twelve months.^[3]

The apparent motion of the Sun observed for six months each in the Northern and the Southern parts of the hemisphere was recorded^[4] and a day named Viṣuva which marked a day and night of equal length which was placed in the middle of the sacrificial year was already discovered in the Brāhmaṇa period.^[5]

The culture followed a lunisolar calendar and the lunar months occurring in one solar year were observed. They being twelve in number is mentioned in Ṛgveda-saṃhitā I. 25.8 and were preferably counted on the basis of Full Moons (Taittirīya-saṃhitā VII.5.6). An additional thirteenth intercalary month also finds mention. (Taittirīya-saṃhitā IV 6.7.1-2, Kauṣitaki-brāhmaṇa 19.2). Tithi, a lunar measurer of time specifying a day and night characterized by the daily rising and setting of Moon is recoginsed.^[6]

The division of a day depended on the Sun and was either from Sunrise to Sunset or from one Sunrise to the next one including a day and a night together termed as an Ahorātra. Such broad divisions of a day as 2, 3 or 5 parts occur in the literature and division of a day (and night) in 30 parts is also mentioned.^[7] Atharvaveda (9.6.46) records the sandhi (joints) of the divisions of the day. A small division of time termed as Abhijit characterized by an (almost) still shadow which constituted the eighth Muhūrta of the day was found out.^[8] Certain minute divisions of time are recorded in the Vedāṅga literature.^[9] Similarly calculations of long time spans such as Yuga,^[10] Kalpa and Manvantara also occur which are employed to specify the comparative time differences between gods and men.

A Saṃvatsara (year) of man is equalled to a day of the gods.^[11] Sahastra (one thousand) Yuga are equalled to a single day of Brahmadeva (Nirukta 14.4). Later in the Purāṇa literature the fourteen Manvantaras together constitute a Kalpa which makes one day of Brahmā^[12] Manusmṛti (I. 68-86) provided an elaborate pattern of Yuga which was followed by the later Jyotiṣa texts.

These calculated year reckonings were practically employed to express important events. Āryabhaṭṭa in Āryabhaṭṭavarṇam refers to the commencement of Mahābhārata war at the end of the Dvāpāra Yuga. Also the characteristics of different Yugas and the events occurring in them are expressed in Manusmṛti and Purāṇa literature.

Footnotes and references:

[1]:

Tai Brā 1.1.2.6,7

[2]:

Ṛgveda-saṃhitā I. 164. 11-13, 48; Śatapatha-brāhmaṇa IX. 1.1.43; Aitareya-brāhmaṇa VII. 7.

[3]:

Taittirīya-saṃhitā IV. 4.11 names the months in accordance with the ṛtus. Mahābhārata (Udyoga Parvas 83.7, Vanaparva 182.16) retains the names of ṛtus but furnishes different. names for months.

[4]:

Taittirīya-saṃhitā VI. 5.3.

[5]:

Aitareya Brāhmaṇa IV. 18.

[6]:

Aitareya Brāhmaṇa 32.10.

[7]:

3 or 5 parts (Tai, Brā. 3.12.9.1, 1.5.3), 30 parts (Taittirīya-brāhmaṇa 3.10.9.).

[8]:

Ādiparva 123.6; Bhāratiya Jyotiṣaśāstra p. 98.

[9]:

Muhūrta and Kṣaṇa (Nirukta 1.25.); Pāṇini mentions Muhūrta (3.3.9.) and perhaps bāḍi (5.4.159.) according to Dikshit, (Bhāratiya Jyotiṣaśāstra, p.102) was a division of time. Also kāṣṭhā and kalā (Śāntiparva 7.2.). Two Nāḍikās = one Muhūrta (Vedāṅga Jyotiṣa. (Ṛgveda-saṃhitā).7.).

[10]:

Yuga comprises a short as well as a long period. History of Dharmaśāstra V. 1 p. 486.

[11]:

Taittirīya-brāhmaṇa 3.9.22.

[12]:

Viṣnu Purāṇa VI. 3.11, 12.