To the White Yajurveda is attached the longest, and, beside the Chhandogya, the most important of the Upanishads. It bears even clearer traces than that work of being a conglomerate of what must originally have been separate treatises. It is divided into three parts, each containing two chapters. The last part is designated, even in the tradition of the commentaries, as a supplement (Khila-kanda), a statement fully borne out by the contents. That the first and second parts were also originally independent of each other is sufficiently proved by both containing the legend of Yajnavalkya and his two wives in almost identical words throughout. To each of these parts (as well as to Book x. of the Çatapatha Brahmana) a successive list (vamça) of teachers is attached. A comparison of these lists seems to justify the conclusion that the first part (called Madhukanda) and the second (Yajnavalkya-kanda) existed during nine generations as independent Upanishads within the school of the White Yajurveda, and were then combined by a teacher named Agniveçya; the third part, which consists of all kinds of supplementary matter, being subsequently added. These lists further make the conclusion probable that the leading teachers of the ritual tradition (Brahmanas) were different from those of the philosophical tradition (Upanishads). Beginning with an allegorical interpretation of the most important sacrifice, the Açvamedha (horse-sacrifice), as the universe, the first chapter proceeds to deal with prana (breath) as a symbol of soul, and then with the creation of the world out of the Atman or Brahma, insisting on the dependence of all existence on the Supreme Soul, which appears in every individual as his self. The polemical attitude adopted against the worship of the gods is characteristic, showing that the passage belongs to an early period, in which the doctrine of the superiority of the Atman to the gods was still asserting itself. The next chapter deals with the nature of the Atman and its manifestations, purusha and prana. The second part of the Upanishad consists of four philosophical discussions, in which Yajnavalkya is the chief speaker. The first (iii. 1-9) is a great disputation, in which the sage proves his superiority to nine successive interlocutors. One of the most interesting conclusions here arrived at is that Brahma is theoretically unknowable, but can be comprehended practically. The second discourse is a dialogue between King Janaka and Yajnavalkya, in which the latter shows the untenableness of six definitions set up by other teachers as to the nature of Brahma; for instance, that it is identical with Breath or Mind. He finally declares that the Atman can only be described negatively, being intangible, indestructible, independent, immovable.