Lord Krishna as saying, in response to the question— "How is Varna (social order) determined?"
"Birth is not the cause, my friend; it is virtues which are the cause of auspiciousness. Even a chandala (lower caste) observing the vow is considered a Brahman by the gods."
“The four fold division of castes’ “was created by me according to the apportionment of qualities and duties.” “Not birth, not sacrament, not learning, make one dvija (twice-born), but righteous conduct alone causes it.” “Be he a Sudra or a member of any other class, says the Lord in the same epic, “he that serves as a raft on a raftless current , or helps to ford the unfordable, deserves respect in everyway.”
Sardar Kavalam Madhava Panikkar (1896-1963) Indian scholar, journalist, historian from Kerala, administrator, diplomat, Minister in Patiala Bikaner and Ambassador to China, Egypt and France. Author of several books, including Asia and Western Dominance, India Through the ages and India and the Indian Ocean.
“The fact is that the four-fold caste is merely a theoretical division of society to which tribes, clans and family groups are affiliated. It is a sociological fiction. The earliest available literature gives instances of Brahmins carrying on the professions of medicine, arms and administration."