Technically you are correct Deepak, Mochi can never be Sunar, but are we comparing castes or are we comparing professions here ?
As far as I think, in todays world even Mochi business as well as Sunar business, are in hands of rich folks. ( Like Liberty, Lakhana, BATA, LaBella and several other thousands ) so looks in we were comparing castes here.
People are shouting in UP, probably people might have felt something... did this ever occur to you ??
