TWO CASTES: Arya and Dasa: When Aryan and non-Aryan tribes settled down and commingled, the tradition of uni-caste society gave way to the bi-caste society of Deva (gods) and Asura (demons) or the Arya and Dasa (master and slave.)

FOUR CASTES: The problem of living was simplified by fire, cattle, and slave. With agriculture, followed by other crafts and trade, life became easier, Prone was the next discovery which further accelerated production.

No longer was there need of hard collective work. Then the Vis itself was split into three parts.

The main body, i.e., the Vaisya followed productive pursuits like agriculture, cattle-rearing, and trade.

The surplus wealth went towards the maintenance of two new castes (varnas) the Brahmana and the Kshatriya, marked not by the colour of their skin but by their profession. The Brahmana performed sacrifices for general Welfare, studied the Vedas and formulated social laws (dharma) on the basis of custom and equity. The Kshatriya was charged with the deference of the realm and the running of the administration.

The three varnas specialized in their avocations and each was accorded a place in the social hierarchy suitable to the dignity of its service. Below the three was the fourth caste of Sudra are Dasa serving the former and no longer an alien race but a subordinate partner within the Aryan system. The Purusa sukta of the Rig-Veda given a mythical story of the origin of the four castes from the mouth, arms, thighs, and feet of the Lord Brahma.

   INTERCHANGE OF CASTE AND OCCUPATION: In the beginning occupations of the varnas were not strictly hereditary. A Kshatriya could excel in philosophical pursuits and become a Brahmana. A well-known story in Vedic literature is that of Visvamitra who was born a Kshatriya but became a Brahmana by acquiring Brahmanical knowledge and virtues. The

Satapatha Brahmana gives a similar story about Janaka, king of Videha. A Brahmana might acquire a kingdom by dint of his valour and become a Kshatriya. He became known as Brahma kshatriya.

In the Matsya Purana the Brahmanas descended from the sage Bhrigu are described as founders of royal houses. The Vaisya and the Sudra could improve their status provided they possessed the necessary talents and virtues. Conversely by choice or by accident, one might be demoted from a higher to a lower caste. The Aitareya Brahmana and the Puranas give instances of these two categories.

Later on, caste and vocation were strictly fixed by heredity according to the laws of the Smrtis. Social and economic divisions were identified and graded.

        The caste system was conceived with a recognition of variations in human nature and as a plan to fit these variations in a graded structure according to the needs of society.