The Kaushitaki Brahmana is a Brahmana (expository commentaries of Brahmanic rituals) of the Bashkala shakha (branch) associated with the Rigveda (most ancient of the pre-Aryan Indic religious texts or Vedas).
These "Brahmanas" (not to be confused with "Brahmin") are required to maintain the purity of the Brahmins through the observance of numerous restrictions, many of which relate to diet and contact with lower castes. Among the Brahmins, one who has studied the Vedas is the best, and among the Brahmins who have studied the Vedas, one who knows the actual purport of Veda is the best. By this means, householder Brahmins who actually abide by the principles of austerity and penance maintain themselves and their families and perform all necessary pious activities." (Further reading: http://www.nationmaster.com/encyclopedia/Brahmana)
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