Some brāhmaṇas are devoted to performing rituals and duties. Some are devoted to austerity. Some are devoted to studying and preaching the Vedas. Some are devoted to jṣāna-yoga. The Fifteenth Chapter describes all the rules for the householder, and ends with a summary. In the previous chapter the superiority of the brāhmaṇa was described. Among the brāhmaṇas there are gradations. The householder fixed in karma is a vipra. When he is fixed in austerity he is a vanaprastha. When he is fixed in study and teaching he is a brahmacārī. When he is fixed in jṣāna-yoga he is a sannyāsī. The word niṣṭhā should be understood to be included with each phrase. The latter are superior to the former in the list.