The caste system can be understood as the combination of two sets of principles – one based on difference and separation and the other based on wholism and hierarchy. These principles work together to create a rigid social structure.

The principle of separation ensures that each caste is strictly separated from every other caste. Scriptural rules prevent the mixing of castes through restrictions on marriage, food sharing, social interaction, and occupation. Castes function as complementary and non-competing groups, where each caste has its own specific place that cannot be taken by any other caste. This creates a social division of labour that allows no mobility.

The principle of hierarchy means that castes do not exist individually but only in relation to a larger whole. The system is hierarchical rather than egalitarian, where each caste occupies not just a distinct place but also an ordered rank in a ladder-like arrangement going from highest to lowest.

This hierarchical ordering is based on the distinction between purity and pollution. Castes considered ritually pure have high status, while those considered impure have low status. Material power is closely associated with social status, and historically, those defeated in wars were often assigned low caste status.

Together, these principles made caste a very unequal institution. Once caste became rigidly determined by birth, it was impossible for individuals to ever change their life circumstances – upper caste persons always retained high status while lower caste persons faced endless labour and subordination.