According to a theory named in Shaivism determinism (niyati), the development of the universe and galaxies as well as that of the species and individuals is determined through temporal cycles.
The civilizations are born and become extinct in accordance with ineluctable rhythms. This is why, most of the times, we can understand the history of humanity only in report with the length of the cycles that determine the life on earth.
The first study of the creation is that of the void, the recipient we could call eternity, because here there is no measure, no length, no before or after.
There is only the Primordial Energy, which, through vibratory waves with direction and length will give birth to the rhythms through which the perception will create the dimension of time, the measure of space and in the same time the structures of matter.
This is why in the Hindu iconography the creation of the world is represented symbolically as produced by the rhythms of Shiva‘s tambourine and through His dance.
For a person, the perception of time is determined by his or her vital rhythms, influenced in their turn by the movement of the sun, moon, and earth, which determine the length of the cycles, years, nights and days.
As perceived by the human being time corresponds to a purely relative length of time, involving a center of perception (the person in question) in a particular world, which is the terrestrial world itself.
Because of this, the “human” time is the only unity of measure that is accessible and understandable to us. Rapported to it, we may estimate the time of the universe, which is, from the perspective of the creative principle only the dream of a day, just as the time of certain atomical universes represents to us only fractions of time.
The laws that govern the development and decline of the universe in its entirety are the same with those that govern each of its parts. This is the reason why we are able to establish a relationship between the time of the universal body of the universal Man, Purusha, and the time of the human being, who is an image, a small-scale model, a reflection of Purusha.
The life of a person is not shorter or longer than that of a God or of the universe. Its length is different only relative terms, as the value of time is given only in rapport with a particular system.
As Linga Purana (writing in which we find precise calculations of the lengths of time of the various cycles) indicates, from Kashta (literally blinking, approximately 1.5 sec) until the length of the universe itself, “Brahma‘s life” or the universe’s life is divided into one thousand great cycles, named Maha-Yuga or the Great Year.
The Maha-Yuga during which the human being appears and then disappears is divided in more than 71 cycles, of Manvantara (approximately 1000 years). Manvantara represents the cycle of a Manu, who gives birth and governs humanity.
Each Manvantara is again divided into 4 ages, or Yuga-s, presenting a gradual decline of spiritual values, in the favor of material progress. Each such age or Yuga is preceded by a period of rising, and is followed by a setting.
These periods of transition (amsha) from the beginning and end of a Yuga last one tenth of the entire period of a Yuga, whose relative lengths are as follows: 4 (Krita Yuga), 3 (Treta Yuga), 2 (Dvapara Yuga), 1 (Kali Yuga) (cf. Linga Purana, 1.4., 3-6).
The first age, Krita Yuga, is the time of divine knowledge and wisom, corresponding to the golden age from Hesiod writings. Then follows Treta Yuga, or the age of the 3 ritual fires, the age of rites, and also of sedentary, agrarian and urban civilization.
The third age, Dvapara Yuga is the age of doubt, which gives birth to contestatary religions and philosophies. The human being loses the sense of the divine reality and becomes distant from the natural law. Then comes the fourth age, Kali Yuga, the decline period of the contemporary humanity, whose dawn we are living at this time.
The work Linga Purana, having as system of reference the human years, manages to present with amazing exactness the dates regarding the present Manvantara. According to the Hindu calendar, if we consider the beginning of Kali Yuga in year 3012 BC and making the necessary calculations, the dawn of Kali Yuga lasts 504.6 years and begins with year 1936 AD.
Thus, we live during the dawns of the age of spiritual decadence, Kali Yuga. These times began, as we mentioned already in 1936 and will end in 2442. According to the Shaivite tradition, since the earth began to be inhabited there were several civilizations living here.
Each of them had their moment of glory, of developing the science and technique and of knowledge. According to this work, we are part of the seventh humankind. Shiva Purana transmits to us, across the millennium the circumstances in which the preceding civilization ended.
This story is a message that we will have to consider with utmost seriousness, in order to learn from the mistakes of our forefathers and in order to avoid making the same mistakes that lead to their destruction.