Time on a very large scale
Most calendars count days, months and years. The Hindu tradition also developed a way of counting that runs into millions and billions of years. Its basic unit is the yuga, an age, and its best-known scheme appears in the Puranas, a body of texts compiled over many centuries, as well as in older epic literature and in works on astronomy. Details vary from text to text, so the figures below are the commonly cited version rather than the only one.
The four ages
There are four yugas, and the names are often linked to the vocabulary of a dice game, in which Krita is the winning throw:
- Krita Yuga, also called Satya Yuga, the age of truth
- Treta Yuga
- Dvapara Yuga
- Kali Yuga, the present age in traditional reckoning
They run in a descending order of quality. In the usual description, dharma, often translated as righteous order or duty, stands on four legs in the first age, three in the second, two in the third and one in the fourth. A bull with decreasing legs is a frequent image for this decline. The tradition presents this as a cosmological and moral story, not a timetable of verifiable events.
The ratio 4:3:2:1
The lengths of the ages are set in the ratio 4:3:2:1. They are first stated in divine years, where one divine year is taken to equal 360 human years:
| Yuga | Divine years | Human years |
|---|---|---|
| Krita | 4,800 | 1,728,000 |
| Treta | 3,600 | 1,296,000 |
| Dvapara | 2,400 | 864,000 |
| Kali | 1,200 | 432,000 |
The four together make 12,000 divine years, which comes to 4,320,000 human years. A set of all four is called a mahayuga, or great age, sometimes also a chaturyuga. In the descriptions that give dawn and dusk periods, those periods are included in the figures above.
The conversion is straightforward: 12,000 multiplied by 360 gives 4,320,000. A divine year of 360 human years follows the idea that a human year is one day of the gods, so 360 days make a divine year.
Larger units: manvantaras, kalpas and the day of Brahma
The Puranic scheme goes much further. In a common version, a thousand mahayugas make a kalpa, which is described as one day of Brahma, the creator figure. That is 1,000 times 4,320,000, or 4,320,000,000 human years. Brahma’s night is said to be of equal length, and Brahma’s life is then counted in such days and nights across a hundred of his years.
Within a kalpa, the texts often divide time into fourteen manvantaras, each presided over by a Manu, the progenitor of humankind for that period. A manvantara is commonly given as seventy-one mahayugas or a little more, and fourteen of them together with the junction periods are meant to approximate the thousand mahayugas of a kalpa. Because the texts give slightly different arithmetic, scholars treat the exact bookkeeping with caution.
The Kali Yuga and a traditional date
In traditional Indian astronomy and in later Hindu usage, the present Kali Yuga is reckoned to have begun at a date corresponding to 3102 BCE. This is a calculated epoch, set backwards from astronomical rules, and is not evidence of an event on that date. Its length of 432,000 years means that, on this reckoning, most of the age lies in the future. Popular writing sometimes turns these figures into predictions about the present day, but the texts themselves are better read as a framework of moral and cosmic order.
Why such big numbers
There is no single agreed reason for the sizes chosen. A few observations can be made without overreaching:
- The numbers are built from simple multipliers: 4, 3, 2, 1, then 1,200, 360 and 1,000. They follow a pattern rather than an observation.
- 432,000 is divisible by 108, giving 4,000. The number 108 is prominent in Indian religious practice, discussed under number 108, but whether the yuga figures were designed around it is not established.
- Indian astronomers did use very large periods in practice, for example to compute planetary positions over huge spans, and they were comfortable writing large numbers thanks to a decimal place-value notation. That background is part of the history of zero.
Large cosmic numbers are not unique to India. Mesoamerican calendars also reached for long counts, and the importance of nine in Hindu cosmology shows that Indian traditions have many numbered schemes beyond the four ages.
Reading the yugas carefully
The yuga scheme is a belief system about cosmic time, with a descending moral order and a cyclical rather than a straight-line history. Its numbers are internal to the tradition and cannot be checked against any geological or historical record. The helpful way to approach it is as one culture’s imaginative answer to the question of how long the world lasts, built from multiplication and ratio, and recorded in texts that sometimes disagree about the details.