William Walker Atkinson,
A Series of Lessons in Gnani Yoga…
“ We cannot go into detail regarding these various cycles, but may mention another division common to the Yogi teachings, beginning with the Great Year. The Great Year is composed of 360 earth years. Twelve thousand Great Years constitute what is known as a Great Cycle, which is seen to consist of 4,320,000 earth years. Seventy-one Great Cycles compose what is called a Manwantara, at the end of which the earth becomes submerged under the waters, until not a vestige of land is left uncovered. This state lasts for a period equal to 71 Great Cycles. ”
