Karma Yoga Sastra -Tilak
THE CONSTRUCTIN AND THE DESTRUCTION OF THE COSMOS
The fixing of the yuga in our present almanacs is based on that method of calculation. This period of twelve thousand years of the gods, is one mahayuga of human beings, or one cycle of four yugas of the gods. Seventy-one such cycles of yugas of the gods make up one ' manvantara ', and there are fourteen such manvantaras. But, at the commencement and the end of the first manvantara and subsequently at the end of each manvantara, there is a conjunctional period equal to one Krta yugas that is to say, there are fifteen such conjunctional periods. These fifteen conjunctional periods and fourteen manvantaras make up one thousand yugas of the gods or one day of Brahmadeva ; and one thousand more such yugas make up one night of Brahmadeva, as has been stated in the Manu-Smrti and in the Mahabharata According to this calculation, one day of Brahmadeva amounts to four hundred and thirty-two crores of human years, that is to say, 4,320,000,000 years. And this is called a ' kalpa ' , When, this day of Brahmadeva or kalpa starts :-
avyaktad vyaktayah sarvah prabhavanty aharagame I
ratryagame praliyante tatraivavyaktasamjnake II 
that is, " all the perceptible things in the universe begin to be created out of the Imperceptible; and when the night of Brahmadeva starts, the same perceptible things again begin to be merged in the Imperceptible", as has been stated in the Bhagavadglts, as also in the Smrti treatises, and elsewhere in the Mahabharata. There are besides this, other descriptions of Cosmic Destruction ( pralaya ) in the Puranas. But as in those pralayas the entire universe, Including the Sun and the Moon, are not destroyed, they are not taken into account in the consideration of the creation and the destruction of the Cosmos. One kalpa means one day or one night of Brahmadeva and 360 such days and 360 such nights make up one of his years, and taking the life of Brahmadeva at one hundred such years, one half of his life is now over and the first day of the second half of his life, that is, of his fifty-first year, or the Svetavaraha kalpa has now- started; and there are statements in the Puranas that out of the fourteen manvantaras of this kalpa, six manvantaras are over, as also 27 mahayugas out of the seventy-one mahayugas of the seventh manvantara called Vaivasvata, and that the first coram, or quarter of the 28th mahayuga of the Vaivasvata manvantara is now going on. In the Saka year 1821, exactly five thousand years of this Kaliyuga were over ; and according to this calculation, there were in the Saka year 1821, three lakhs and ninety-one thousand years still in hand for the pralaya in the Kaliyuga to take place ; therefore, the consideration of the Mahapralaya to take place at the end of the present kalpa is a far, far, distant thing. The day of Brahmadeva, made up of four hundred and thirty- two crores of human years, is now going on and not even the noon of that day, that is to say, seven manvantaras are yet over.
References And Context
- (Surya-Siddhanta 1. 15-20)
- (Manu. 1. 69-73 and 79; Ma. Bha. San. 231. 18-31 and the Nirukta by Yaska 14. 9).
- A calculation of yugas etc. according to astrological science has been made by the late Shankar Balkrishna Dikshit in his work Bharatiya Jyotihsastra in various places to which the reader is referred. See pages 103 to 105 and p. 193 etc.
- (Gi. 8. 18).
- (GI. 8. 18 and 9. 7)
- (See Visnu-Purana 1. 3)