recite shastras (litanies): , brāhmanācchamsin, maitrāvaruna, , , agnīdh and acchāvāka. They also carry a legend to explain the origin of the offices of the subrahmanya and the grāvastut. Purohita The requirements of the fully developed ritual were rigorous enough that only professional priests could perform them adequately. Thus, whereas in the earliest times, the true sacrificer, or intended beneficiary of the rite, might have been a direct participant, in Vedic times he was only a sponsor, the yajamāna, with the or brahman taking his stead in the ritual. In this seconding lay the origins of the growing importance of the purohita (literally, "one who is placed in front"). It was not unusual for a purohita to be the or brahman at a sacrifice for his master, besides conducting other more domestic () rituals for him also. In latter days, with the disappearance of Vedic ritual practice, purohita has become a generic term for "priest". Assistants In the systematic expositions of the shrauta sutras, which date to the fifth or sixth century BCE, the assistants are classified into four groups associated with each of the four chief priests, although the classifications are artificial and in some cases incorrect: With the : the maitrāvaruna the acchāvāka the grāvastut (praising the Soma stones) With the : the (who chants the Prastâva) the ("averter") the subrahmanya With the adhvaryu: the the the (who pours the Soma juice into the receptacles ) With the brahman: the brāhmanācchamsin the agnīdh (priest who kindles the sacred fire) the ("purifier") Philological comparisons Comparison with the sacred texts of Zoroastrianism, a distinct religion with the same origins, shows the antiquity of terms for priests such as *atharwan (Vedic atharvan; cognate to Avestan ) and *zhautar (Ved. hotar; Av. ) 'invoker, sacrificer'. While *zhautar is well understood, the original meaning of *atharwan is unknown. The word atharvan appears in the Rig Veda (e.g., in RV 6.16.13 where Agni is said to have been churned by Atharvan from the mind of every poet). In the Younger Avesta, appears in a context that suggests "missionary," perhaps by metathesis from Indo-Iranian *arthavan "possessing purpose." However, a recent theory indicates that Proto Indo-Iranian *atharwan likely represents a substrate word from the unknown language of the BMAC civilization of Central Asia. It can be analyzed as BMAC *athar- plus the Indo-Iranian possessive suffix *-wan, in which case *atharwan would be "one who possesses *athar".