They were allowed to survive for public use and property only because they were and are absolutely unintelligible to the masses. Otherwise they would have disappeared from circulation as long ago as the days of Akbar" (SD 1:68). Though the Brahmanas are the oldest scholastic treatises on the primitive hymns, they themselves require a key for a proper understanding of them which Orientalists have hitherto failed to secure. Since the time of Gautama Buddha, the keys to the Brahmanical secret code have been in the possession of initiates alone, who guard their treasure with extreme and jealous care. There are indeed few, if any, individuals of the present-day Brahmanical cast in India who are even conscious that such keys exists; although no small number of them, possibly, have intimations or intuitions that a secret wisdom has been lost which is uniformly understood to have been in the possession of the ancient Indian rishis.
Brahmana is also the adjectival form for the two uses given above.
See also CHATUR-VARNA