In his Institutes, Manu says- The Brahmana primarily sprang from the mouth of Brahma. This original Brahmana according to the ordinance married a woman of the same caste, and the offspring of this connection go by the name of Brahmanas. The duties of a Brahmana are celebrating sacrifice, officiating at other's sacrifices, study, teaching, making gifts, and, finally, receiving such. Of these, officiating as priests, teaching and receiving clean gifts...