A mundane period of years, four of which have already passed, making up an aggregate of four million solar years. In the first period men were innocent and free from disease, in the second their life was shortened by one quarter. In the first period devotion was man's object, in the second spiritual knowledge, in the third sacrifice. Compare the Hindu legend with the account given in Genesis.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894