As per the Indian believe the Vedas contains all the aspects of knowledge.
As refered “catur varnyam trayo lokamscasramas ca prthak prthak bhutam bhavyam bhavisyam ca sarvam vedat prasidhyati.” means the four varnas and ashramas exist in the three worlds in the past, present, and the future also. This is explained in the Vedas.”