Yuga (devanāgarī: युग) is a Sanskrit word meaning 'epoch' or 'era' used in Hindu philosophy to refer to a cycle of four ages called Satya Yuga, Treta Yuga, Dvapara Yuga, and Kali Yuga. The total of the said four Yugas is called Maha Yuga.
H. P. Blavatsky said that "the exoteric figures accepted throughout India . . . dovetail pretty nearly with those of the Secret works" so she gives the duration of the yugas as rendered in the Hindu books:
Krita Yuga: 1,728,000 years
Treta Yuga: 1,296,000 years
Dwapara Yuga: 864,000 years
Kali Yuga: 432,000 years
Maha Yuga: 4,320,000 years
Kali Yuga (Devanāgarī: कलियुग) literally means the "age of Kali" and it is frequently referred as the "black age". This is the age humanity is currently in. According to the Surya Siddhanta, Kali Yuga began at midnight (00:00) on 18 February 3102 BCE, a date also considered by many Hindus to be the day that Krishna left Earth to return to his abode. Mme. Blavatsky wrote:
Kaliyuga (Sk). The fourth, the blaek or iron age, our present period, the duration of which is 432,000 years. The last of the ages into which the evolutionary period of man is divided by a series of such ages. It began 3,102 years B.C. at the moment of Krishna's death, and the first cycle of 5,000 years will end between the years 1897 and 1898.
Those who have watched mankind through the centuries of this cycle, have constantly seen the details of this death-struggle between Truth and Error repeating themselves. Some of you Theosophists are now only wounded in your "honour" or your purses, but those who held the lamp in preceding generations paid the penalty of their lives for their knowledge.
We are at the very close of the cycle of 5,000 years of the present Aryan Kaliyuga; and between this time and 1897 there will be a large rent made in the Veil of Nature, and materialistic science will receive a death-blow.
The world moves in cycles, which proceed under the impetus of two mutually antagonistic and destroying Forces, the one striving to move Humanity onward, toward Spirit, the other forcing Mankind to gravitate downward, into the very abysses of matter. It remains with men to help either the one or the other. Thus, also, it is our present task, as Theosophists, to help in one or the other direction. We are in the very midst of the Egyptian darkness of Kali-yuga, the "Black Age," the first 5,000 years of which, its dreary first cycle, is preparing to close on the world between 1897 and 1898. Unless we succeed in placing the T.S. before this date on the safe side of the spiritual current, it will be swept away irretrievably into the Deep called "Failure," and the cold waves of oblivion will close over its doomed head. Thus will have ingloriously perished the only association whose aims, rules and original purposes answer in every particular and detail--if strictly carried out--to the innermost, fundamental thought of every great Adept Reformer, the beautiful dream of a UNIVERSAL BROTHERHOOD OF MAN.
- Helena Petrovna Blavatsky, Secret Doctrine vol. II, (Wheaton, Ill: Theosophical Publishing House, 1993), 69-70
- Helena Petrovna Blavatsky, The Theosophical Glossary (Krotona, CA: Theosophical Publishing House, 1973), 170.
- Vicente Hao Chin, Jr., The Mahatma Letters to A.P. Sinnett in chronological sequence No. 130 (Quezon City: Theosophical Publishing House, 1993), ???.
- Helena Petrovna Blavatsky, The Secret Doctrine vol. I, (Wheaton, IL: Theosophical Publishing House, 1993), 612.
- Helena Petrovna Blavatsky, Collected Writings vol. XII (Wheaton, IL: Theosophical Publishing House, 1980), 418.