E. Sumod Mohan: Yugas

The traditional virtues accorded the highest value in the four epochs are:
Satya Yuga or Krita Yuga: dhyana (meditation). In the highest yuga, the great majority of people can experience spirituality by direct intuitive realization of truth. The veil between the material and the transcendent realms becomes almost transparent. According to Natya Shastra, there are no Natya performances in the Krita Yuga because it is a period free from any kind of unhappiness or misery. Satya Yuga is also called the Golden Age.
Treta Yuga: yajna (sacrifice). Treta Yuga is the mental age. Mental power is harnessed and men are in power, there are inventions that dissolve the illusion of time (inventions are characteristic of both Dvapara and Treta yugas.) Clairvoyance and telepathy are common knowledge.
Dvapara Yuga: archana (worship). In Dvapara Yuga, science flourishes, people experience the spiritual in terms of subtle energies and rational choices, inventions are abundant, particularly those that dissolve the illusion of distance (between people and between things), and power is mostly in the hands of women. The end of this age (in the descending phase) is associated with the death of Krishna, and the events described in the Mahabharata.
Kali Yuga: daana (alms). In the lowest epoch, Kali Yuga, most people are aware only of the physical aspects of existence, the predominant emphasis of living is material survival, and power is mostly in the hands of men. Men have no knowledge of electricity, magnetism or subtle forces of nature. People's relationship with the spiritual is governed predominantly by superstition and by authority.
Temples, wars, and writing are hallmarks of Dvapara and Kali yugas. In the higher ages (Treta and Satya), writing is unnecessary because people communicate directly by thought; temples are unnecessary because people feel the omnipresence of God; wars are rare but they do occur - one such war is described in the Ramayana.
The Hindu texts[citation needed] say the four yugas equal 4,320,000 years, or a mahayuga. 1,000 mahayugas or 4.32 billion years equal one kalpa. The traditional[citation needed] timescale of the yugas is as follows:
Satya Yuga or Krita Yuga - 1,728,000 years
Treta Yuga - 1,296,000 years
Dvapara Yuga - 864,000 years
Kali Yuga - 432,000 years
Hence, Hindu scripture says[citation needed] the length of the yugas maintain a 4,3,2,1 ratio to each other, with the Krita or Satya lasting 4000 years (plus a 400 year transition in and out) for a total of 4800 years, the Treta equals 3000 years (plus a 300 year transition in and out) for a total of 3600 years, the Dwapara last 2000 years (plus a 200 year transition in and out) for a total of 2400 years and the Kali 1000 years (plus a 100 year transition in and out) for a total of 1200 years. All the epochs together equal 12,000 years (or divine years) in the ascending phase and 12,000 years in the descending phase. One complete cycle is said to be equal to, and celestially observed as one precession of the equinox, according to Sri Yukteswar (see below). This four yugas consists of 10 parts of 432,000 years i.e 4,320,000 years . The Krita Yuga lasts for 4 parts; the name has the same consonants T and R of the word Chatur (four). The Threta Yuga consists of Tri (three) parts as it is apparent in the name 'Treta'. The Dvapara Yuga lasts for Dva (two) parts as it is apparent in the name 'Dvapara'. The Kali Yuga lasts for Eka (one) part; the consonant K appears in the name Kali.
Upon conclusion of seventy-one circuits of this cycle, there is a period equally long during which the world is inundated; then the cycle begins again.