There is nothing called low-caste and high-caste. It is a distortion of the original concept. The idea is in order to run a society or even a indivdual properly one needs to imbibe 4 basic qualities of - Thinker (Bramhin), Protector (Kshatriya), Economist (Vaishya), Worker (Shudra). All of them are equal and do not exist in isolation. Even in life one has to imbibe all the 4 qualities to be successful. This concept will always be true everywhere in whatever profession people pursue. It has been distorted and abused by confused people over time.