Synopsis The Portuguese usage of caste refers only to lineage and does not refer to any particular kind of division of grouping, purity or pollution. The genesis of caste is to be settled by comparative evidence and not based upon only on the verses of Rigveda. The four fold varna is elastic as per laws of Manu but sociologists and historians now believe they know more about the ancients than ancients themselves. The caste is in its nature rather a matter of sociology than religion. Sir James Lyallin nineteenth century has observed "One can observe caste growing before his eyes; the noble is changing into Rajput, the priest into Brahman, the peasant into a Jat; and so on down to the bottom of the scale". Even now process of caste formation is going on. No final decision has ever been made as to what constitutes a caste. It is too easily assumed that the caste label is fixed for ever. But caste is conditioned by human activity, and nature does not allow any rigid system to survive.