As regards the other two "twice-born" castes, several modern groups do indeed claim to be their direct descendants, and in vindication of their title make it a point to perform the _upanayana_ ceremony and to wear the sacred thread. But though the Brahmans, too, will often acquiesce in the reasonableness of such claims, it is probably only as a matter of policy that they do so, whilst in reality they regard the other two higher castes as having long since disappeared and been merged by miscegenation in the Sudra mass. Hence, in the later classical Sanskrit literature, the term _dvija_, or twice-born, is used simply as a synonym for a Brahman. As regards the numerous groups included under the term of Sudras, the distinction between "clean" and "unclean" Sudras is of especial importance for the upper classes, inasmuch as only the former--of whom nine distinct castes are usually recognized--are as a rule considered fit for employment in household service. Theology. The picture thus presented by Hindu society--as made up of a confused congeries of social groups of the most varied standing, each held together and kept separate from others by a traditional body of ceremonial rules and by the notion of social gradations being due to a divinely instituted order of things--finds something like a counterpart in the religious life of the people. As in the social sphere, so also in the sphere of religious belief, we find the whole scale of types represented from the lowest to the highest; and here as there, we meet with the same failure of welding the confused mass into a well-ordered whole. In their theory of a triple manifestation of an impersonal deity, the Brahmanical theologians, as we have seen, had indeed elaborated a doctrine which might have seemed to form a reasonable, authoritative creed for a community already strongly imbued with pantheistic notions; yet, at best, that creed could only appeal to the sympathies of a comparatively limited portion of the people. Indeed, the sacerdotal class themselves had made its universal acceptance an impossibility, seeing that their laws, by which the relations of the classes were to be regulated, aimed at permanently excluding the entire body of aboriginal tribes from the religious life of their Aryan masters. They were to be left for all time coming to their own traditional idolatrous notions and practices. However, the two races could not, in the nature of things, be permanently kept separate from each other. Indeed, even prior to the definite establishment of the caste-system, the mingling of the lower race with the upper classes, especially with the aristocratic landowners and still more so with the yeomanry, had probably been going on to such an extent as to have resulted in two fairly well-defined intermediate types of colour between the priestly order and the servile race and to have facilitated the ultimate division into four "colours" (_varna_). In