B. R. Ambedkar

Caste is not a physical object like a wall of bricks or a line of barbed wire which prevents the Hindus from co-mingling and which has, therefore, to be pulled down. Caste is a notion; it is a state of the mind.

I think one of the most important directions to be pursued in the 'sciences of human action' is to develop a natural-law ethics based on nature rather than, or at least to supplement, ethics based on theological revelation.