Yuga (Devanāgari: युग) in Hindu philosophy is the name of an 'epoch' or 'era' within a cycle of four ages. These are the Satya Yuga (or Krita Yuga), the Treta Yuga, the Dvapara Yuga and finally the Kali Yuga. According to Hindu cosmology, the world is created, destroyed and recreated every 4,320,000 years (Maha Yuga) [1]. The cycles are said to repeat like the seasons, waxing and waning within a greater time-cycle of the creation and destruction of the universe. Like Summer, Spring, Winter and Autumn, each yuga involves stages or gradual changes which the earth and the consciousness of mankind goes through as a whole. A complete yuga cycle from a high Golden Age of enlightenment to a Dark Age and back again is said to be caused by the solar system's motion around a central sun
Satya Yuga
The Satya Yuga (Devanagari: सत्य युग), also called Sat Yuga, Krta Yuga and Krita Yuga in Hinduism, is the "Yuga (Age or Era) of Truth", when mankind is governed by gods, and every manifestation or work is close to the purest ideal and mankind will allow intrinsic goodness to rule supreme. It is sometimes referred to as the "Golden Age." The average lifespan in the satya yuga is 100,000 years
Amongst the four eras, the Satya Yuga is the first and the most significant one. Knowledge, meditation, and penance hold special importance in this era. All the pillars of religion are present in totality. The average life expectancy of a human being in Satya Yuga is believed to be over 100,000 years. During Satya Yuga, all people engage only in good, sublime deeds.
...as described in the Mahabharata
[...] there were no poor and no rich; there was no need to labour, because all that men required was obtained by the power of will; the chief virtue was the abandonment of all worldly desires. The Krita Yuga was without disease; there was no lessening with the years; there was no hatred or vanity, or evil thought; no sorrow, no fear. All mankind could attain to supreme blessedness. [...]
Treta Yuga
The Treta Yuga (Devanagari: त्रेता युग)is the second out of four yugas, or ages of man, in the religion of Hinduism, following the Satya Yuga of perfect morality and preceding the Dvapara Yuga. The most famous events in this yuga were Lord Vishnu's fifth, sixth and seventh incarnations as Vamana[1], Parashurama and Ramachandra respectively. The Dharma bull, which symbolises morality, stood on three legs during this period. It had all four in the Satya Yuga and two in the later Dvapara Yuga. Currently, in the immoral age of Kali, it stands on one leg
Avatars of Vishnu during Treta Yuga
Vamana
Vishnu incarnated as the dwarf son of Aditi to stop King Mahabali of the Asura race, the grandson of Prahlada, from completing a sacrifice which would allow him to overshadow Devendra in power and splendor. The jealous and worried Devas persuaded Vishnu to send Bali, a bhakta of his, to Patala, the underworld. Vishnu did so by taking advantage of the King's kindness and refusal to go back on his word, but allowed him a luxurious dwelling and sovereignty in one of the lower worlds. He also gave him the boon of being able to visit his subjects once every year.
Parashurama
Vishnu incarnated as the Brahmana Parashurama in this era[3] because there were too many warlike kshatriyas plaguing the Earth, and he therefore had to wipe out most of the world's warriors. However, some of the Kshatriyas survived or more were created, and their population grew again. Eventually, the avatara of Vishnu in Parashurama ended, though it is said that he continued to live on as a mighty warrior-hermit. He confronted Ramachandra angrily years later, before acknowledging the latter's supremacy and retiring. He lived on in the Dvapara Yuga, having a great duel with Bhishma for Amba's sake (and losing), and he taught Karna how to use the Brahmastra and cursed him when he found out that he was not a Brahmin but a kshatriya. He had vowed not to teach or be a Guru of Kshatriyas. He is said to be still alive today, meditating in the mountains or deep in a forest.
Ramachandra
The hallmark of this era was the rise of evil in the form of the demon king of Lanka, Ravana. He conquered the three worlds namely, earth, heavens and the netherworlds (patala) and terrorized everyone. Even the Devas were subordinate to him - his son Meghanada had earned the name of Indrajit by defeating Indra, the King of heaven, in battle; and even the Sun had to obey the rakshasa king. In this scenario, Lord Vishnu incarnated himself as the son of King Dasaratha of the Sun Dynasty or Ikshvaku dynasty and was named Lord Rama. Due to a stepmother's jealousy, Lord Rama was sent away to the forest in exile for 14 years, during which time he confronted and killed Ravana for having kidnapped his wife, and thus restored peace on earth. He is said to have afterwards ruled the Kingdom of Kosala from Ayodhya for an eleven-thousand year golden age known as the Rama-rajya or Rama's Kingdom, before eventually returning to his Mahavishnu form with his three half-brothers- Lakshmana, Bharata and Shatrughna- who were "minor" incarnations of Vishnu or the great serpent-god Shesha.
Dvapara Yuga
Dvapara Yuga or Dwapara Yuga[1](Devanagari: द्वापर युग) is the third out of four yugas, or ages, described in the scriptures of Hinduism. This yuga comes after Treta Yuga and is followed by Kali Yuga. According to the Puranas this yuga ended at the moment when Krishna returned to his eternal abode of Vaikuntha.[2]
There are only two pillars left of religion in the Dvapara Yuga. Bhagavan Vishnu assumes the yellow color and the Vedas are categorized into four parts that is Rig, Sama, Yajur and Atharva. During these times the Brahmins are knowledgeable of two, sometimes three Vedas, but rarely have studied all the four Vedas thoroughly. Accordingly, because of this categorization, different actions and activities come into existence
The roles of the castes
All people in the Dvapara Yuga are zealous, valiant, courageous and competitive by nature and are engaged only in penance and charity. They are kingly and pleasure-seeking. In this era, the divine intellect ceases to exist, and it is therefore seldom that anyone is wholly truthful. As a result of this life of deceit, people are plagued by ailments, diseases and various types of desires. After suffering from these ailments, people realize their misdeeds and perform penance. Some also organize Yagya for material benefits as well as for divinity.
Brahmana
In this Yuga, the Brahmanas who are through a fallacy referred to as Brahmins are involved in Yagya, self-study, donation and teaching activities. They attain celestial bliss by engaging in penance, religion, control of senses and restraint.
Kshatriya
The duties of Kshatriyas are the protection of their subjects. In this era, they are humble and perform their duties by controlling their senses. The Kshatriyas honestly execute all policies of law and order without being angry or cruel. They are devoid of greed and consequently attain bliss.
The king avails the advice of the learned scholars and accordingly maintains law and order in his empire. The king who is addicted to vices will definitely end up defeated. One or two or all from Sāma, Dāna, Danda, Bheda and Upeksha is/are brought into use and help attain the desired. Kings are diligent in maintaining public decorum and order.
A few of the kings, however, surreptitiously plan a conspiracy along with the scholars. Strong people execute work where execution of policies is involved. The king appoints priests, etc. to perform religious activities, economists and ministers to perform monetary activities, impotents to take care of women and cruel men to execute heinous activities.
There are two kshatriya dynasties, namely 'Surya Vansha' and 'Chandra Vansha'.
Vaishya
Vaishyas are mostly landowners and merchants. The duties of Vaishyas are trade and agriculture. Vaishyas attain higher planes through charity and hospitality.
Shudra
The duty of Shudras is to perform tasks that demand highly physical work. Although their form of labour is different from the other three castes, the Shudras are not discriminated against. In fact Vidura, the famous Prime Minister of Hastinapura was born in the Shudra community and attained the status of a Brahmin due to his wisdom, righteousness and learning. All other three sections namely Brahmana, Kshatriya and Vaishya protected Shudras and contributed for their safety and happiness. Krishna, eighth avatar of Vishnu was brought up in a Vaishya family though he was a born Kshatriya.
The living and moral standard of the people overall in the Dvapara Yuga drops immensely from the Treta Yuga. The average life expectancy of humans begins to fall to only 1,000 years in this era because of neglect of the Varnashram, Vedas and Yagyas. The Vedas especially become less active
Kali Yuga
Kali Yuga (Devanāgarī: कलियुग, lit. "Age of Kali", "age of vice"). Kali Yuga began at midnight (00:00) on 18 February 3102 BCE [1] in the proleptic Julian calendar or 23 January 3102 BC in the proleptic Gregorian calendar, which is also considered by many Hindus to be the time that Krishna, an incarnation of Vishnu, died as a result of a freak bow hunting accident. The Kali Yuga is traditionally thought to last 432,000 years.
In The Aihole Inscription 3735 years after the Bharata war is equated with 556 years of the Saka Era, in the Kali Yuga. This would mean 3179 years after the Bharata war, the Saka Era started. Whitaker's alamanac says that Year 1922 in the Saka calendar is 2000 AD/CE. So the Saka year started in 78 BC. That would imply that the Kaliyuga started in 3179-78= 3101 BC.
Hinduism generally considers morality to be comparable to a bull known as Dharma. In Satya Yuga, the first stage of development, the bull had four legs, and in each age morality is reduced by a quarter. By the age of Kali, morality will be reduced to only a quarter of that of the golden age. Thus, the bull will only have one leg: morality will wait on men
Kali Yuga is associated with the apocalypse demon Kali, not be confused with the goddess Kālī, as these are unrelated words in the Sanskrit language. The "Kali" of Kali Yuga means "strife, discord, quarrel, or contention."
Attributes of Kali Yuga
Various Puranas (like Bhagavata 12.2) give lists of Kali Yuga symptoms. Some of them are:
Rulers will become unreasonable: they will levy taxes unfairly. Rulers will no longer see it as their duty to promote spirituality, or to protect their subjects: they will become a danger to the world. People will start migrating, seeking countries where wheat and barley form the staple food source.
Avarice and wrath will be common, men will openly display animosity towards each other. Ignorance of Dharma will occur. Lust will be viewed as being socially acceptable. People will have thoughts of murder for no justification, and they will see nothing wrong with that mind-set.
People will be inclined to follow false sciences. Family murders will also occur. People will see those who are helpless as easy targets and remove everything from them.
Many other unwanted changes will occur. The right hand will deceive the left, and the left the right. Men with false reputation of learning will teach the Truth. The old will betray the innocence of the young, and the young will betray the dotage of the old. Cowards will have a reputation for bravery, and the brave will be enervated cowards. People will not trust anyone in the world, not even their immediate family. Husband and wife will find contempt in each other.
In Kali Yuga, even pre-teenage girls will get pregnant. The primary cause will be the social acceptance of sexual intercourse as being the central requirement of life.
It is believed that sin will increase exponentially, whilst virtue will fade and cease to flourish. People will take vows only to break them soon after.
Death and famine will be everywhere. Men will have lustful thoughts, and so will women. People will without reason destroy trees and gardens. Men will commit murder. There will be no respect for animals, and meat eating will start.
People will become addicted to intoxicating drinks. Men will find their jobs stressful and will go to retreats to escape their work.
Gurus will no longer be respected and their students will attempt to injure them. Their teachings will be insulted and followers of Kama will wrest control of the mind from all human beings.
As the sin increases exponentially, so will the incidence of divine justice and wrath.
when flowers will be begot within flowers, and fruits within fruits, then will the Yuga comes to an end. And the clouds will pour rain unseasonably when the end of the Yuga approaches.
Personification
Kali (Devanāgari: कलि) is the reigning lord of Kali Yuga, and the nemesis of Sri Kalki, the 10th and final avatar of Lord Vishnu. According to the Vishnu Purana, he is a negative manifestation of Vishnu who, along with his extended evil family, perpetually operates as a cause of the destruction of this world.[6] He serves as an antagonistic force in the Kalki Purana.
Towards the end of this yuga, Kalki will come riding on a white horse to battle Kali and his dark forces. The world will suffer a fiery end which will destroy all evil, and a new age, Satya Yuga, will begin.
