Brahmacarya is contextualized by āśrama: for the brahmacārin (Vedic student), the yati (renunciate), and the naiṣṭhika (lifelong celibate), strict celibacy is prescribed. For the forest-dweller (araṇyavāsin), the same standard applies. This verse establishes that brahmacarya in its strict form is the norm for three of the four āśramas — only the gṛhastha is excepted.