<P> According to Basham, ancient Indian literature refers often to varnas, but hardly if ever to jatis as a system of groups within the varnas . He concludes that "If caste is defined as a system of group within the class, which are normally endogamous, commensal and craft - exclusive, we have no real evidence of its existence until comparatively late times ." </P> <P> The Vedic texts neither mention the concept of untouchable people nor any practice of untouchability . The rituals in the Vedas ask the noble or king to eat with the commoner from the same vessel . Later Vedic texts ridicule some professions, but the concept of untouchability is not found in them . </P> <P> The post-Vedic texts, particularly Manusmriti mentions outcastes and suggests that they be ostracised . Recent scholarship states that the discussion of outcastes in post-Vedic texts is different from the system widely discussed in colonial era Indian literature, and in Dumont's structural theory on caste system in India . Patrick Olivelle, a professor of Sanskrit and Indian Religions and credited with modern translations of Vedic literature, Dharma - sutras and Dharma - sastras, states that ancient and medieval Indian texts do not support the ritual pollution, purity - impurity premise implicit in the Dumont theory . According to Olivelle, purity - impurity is discussed in the Dharma - sastra texts, but only in the context of the individual's moral, ritual and biological pollution (eating certain kinds of food such as meat, going to bathroom). Olivelle writes in his review of post-Vedic Sutra and Shastra texts, "we see no instance when a term of pure / impure is used with reference to a group of individuals or a varna or caste". The only mention of impurity in the Shastra texts from the 1st millennium is about people who commit grievous sins and thereby fall out of their varna . These, writes Olivelle, are called "fallen people" and considered impure in the medieval Indian texts . The texts declare that these sinful, fallen people be ostracised . Olivelle adds that the overwhelming focus in matters relating to purity / impurity in the Dharma - sastra texts concerns "individuals irrespective of their varna affiliation" and all four varnas could attain purity or impurity by the content of their character, ethical intent, actions, innocence or ignorance (acts by children), stipulations, and ritualistic behaviors . </P> <P> Dumont, in his later publications, acknowledged that ancient varna hierarchy was not based on purity - impurity ranking principle, and that the Vedic literature is devoid of the untouchability concept . </P>

Four category of the system used in india