or sectarian associations, who wished to have an Upanishad of their own in imitation of the old Vedic schools. They became attached to the Atharva-veda not from any internal connection, but partly because the followers of the Atharva-veda desired to become possessed of dogmatic text-books of their own, and partly because the fourth Veda was not protected from the intrusion of foreign elements by the watchfulness of religious guilds like the old Vedic schools.
The fundamental doctrine common to all the Upanishads of the Atharva-veda is developed by most of them in various special directions. They may accordingly be divided into four categories which run chronologically parallel with one another, each containing relatively old and late productions. The first group, as directly investigating the nature of the Ātman, has a scope similar to that of the Upanishads of the other Vedas, and goes no further than the latter in developing its main thesis. The next group, taking the fundamental doctrine for granted, treats of absorption in the Ātman through ascetic meditation (yoga) based on the component parts of the sacred syllable om. These Upanishads are almost without exception composed in verse and are quite short, consisting on the average of about twenty stanzas. In the third category the life of the religious mendicant (sannyāsin), as a practical consequence of the Upanishad doctrine, is recommended and described. These Upanishads, too, are short, but are written in prose, though with an admixture of verse. The last group is sectarian in character, interpreting the popular gods Çiva (under various names, such as Īçāna, Maheçvara, Mahādeva) and Vishṇu (as Nārāyaṇa and Nṛisiṃha or "Man-lion") as personifications
