Hindus believe that the world is created, destroyed, and re-created in an eternally repetitive series of cycles.
In Hindu cosmology a universe endures for about 4,320,000,000 years (one day of Brahma or kalpa) and is then destroyed by fire or water. At his point, Brahma rests for one night, just as long as the day. This process, named pralaya, repeats for such 100 years, period that represents Brahma's lifespan.
After Brahma's "death", it is necessary that another 100 of his years pass until he is reborn and the whole creation begins anew. This process is repeated again and again, forever.
Brahma's life is divided in one thousand cycles (Maha Yuga, or the Great Year). Maha Yuga, during which the human race appears and then disappears, has 71 divisions, each made of 14 Manvantara (1000) years. Each Maha Yuga lasts for 4,320,000 years. Manvantara is Manu's cycle, the one who gives birth and govern human race.
Each Maha Yuga consists of a series of four shorter yugas, or ages. The yugas get progressively worse from a moral point of view as one proceeds from one yuga to another. As a result each yuga is of shorter duration than the age that preceded it.
| Yuga | Duration
(years) | God | Virtue |
| | 1,728,000 | Brahma | Meditation |
| | 1,296,000 | Vishnu | Knowledge |
| | 864,000 | Vishnu | Sacrifice |
| | 432,000 | Vishnu
Shiva-Rudra | Charity |
|
| 4,320,000 |
|
|
Kriti Yuga is the first yuga of a Maha Yuga. This is the age of virtue and moral perfection. It is a bright, golden age on earth. The great god Vishnu, in his form of Brahma, the creator of the world, is the presiding god, and dharma (ideal, righteous behavior or moral duty) walks steadily and securely upon all four feet.
The Krita Yuga lasts for 1,728,000 years.
During Kritia Yuga, human beings need no shelters. There are no shortage of food. Gift-giving trees provide them with an abundant supply of food, clothing, and decorative objects. Everyone is born good and lives a happy, contented, unselfish, and beautiful life.
People are devoted to meditation, the highest virtue, and spend their lives being loyal to dharma. They work for the pleasure of it, rather than from necessity. Sorrow does not exist.
Treta Yuga is the second age in each Maha Yuga.
Treta means three. During this yuga, dharma walks less steadily, on three of its four feet. Virtue and moral perfection still exist, but they have declined by one-fourth. The duration of the age has similarly declined by one-fourth to 1,296,000 years.
Vishnu, the preserver of life on earth, is the presiding god during Treta Yuga.
People are devoted to the pursuit of knowledge, which they consider the highest virtue.
As in Kriti Yuga, the gift-giving trees supply food and clothing to everyone in abundance during the Treta Yuga. But greedy people try to make the trees their private property. When that happens, the special trees disappear, and life on earth becomes difficult for the first time. Heavy rainfall creates rivers. The soil is fertile for the growth of many new kinds of trees. The new trees bear fruit; but as opposed to the gift giving trees, these are ordinary trees. People must work hard to acquire food and clothing. Because of the rain and severe changes in the weather, they also need to construct houses for shelter.
In the Treta Yuga people are more passionate and greedy. They are no longer happy with what they have. Dissatisfaction, resentment, and anger replace satisfaction, peace, and contentment in their hearts. They covet their neighbors' possessions. The strong take land from the weak in order to possess more food and greater wealth. Many men take the wives of others.
Dvapara Yuga is the third age in each Maha Yuga.
As the name Dva suggests (Dva means two), eternal dharma now has to balance on two of its four feet, creating a precarious and shifting balance between good and evil. Virtue and moral perfection still exist, but they have declined to one-half of what they were in the Krita Yuga. As a result, the duration of this age is half that of the Krita Yuga (864,000 years).
Vishnu, the preserver of life on earth, is still the presiding god during Dvapara yuga. People devote themselves to sacrifice, which they consider the highest virtue.
In the Dvapara Yuga, disease, misfortune, suffering, and death are part of everyone's existence. People have become more passionate and greedy, and war is commonplace. Religious doctrines are developed in an attempt to guide human behavior toward dharma, but the gradual process of moral deterioration continues.
Kali Yuga is the fourth age in each Maha Yuga. Kali means quarrel and war. This is the dark age. Dharrna has to stand on only one of its four feet, and virtue barely exists. This age is only one-fourth the length of the Krita Yuga (432,000 years).
Vishnu is still the presiding god, in his form of Shiva-Rudra, the destroyer of life on earth.
In the Kali Yuga people achieve noble rank in society based on the amount of money and property they own rather than their moral virtue. The quality of virtue is measured only in terms of material wealth. Sexual passion alone binds husband and wife together in marriage. People become successful in life through a succession of lies, and their only source of enjoyment is sex. They live with continuous fear of hunger, disease, and death.
In the Kali Yuga only the poor are honest, and the only remaining virtue is charity.
Harsh weather and primitive living conditions make them prey to devastating illnesses. One who attains the age of twenty-three is considered very old.
