Caste is a state of mind. It is a disease of mind. The teachings of the Hindu religion are the root cause of this disease. We practice casteism and we observe Untouchability because we are enjoined to do so by the Hindu religion. A bitter thing cannot be made sweet. The taste of anything can be changed. But poison cannot be changed into nectar.
It is a celebrated thought of Socrates, that if all the misfortunes of mankind were cast into a public stock, in order to be equally distributed among the whole species, those who now think themselves the most unhappy would prefer the share they are already possessed of, before that which would fall to them by such a division. [as they realise their problems could be worse!]