According to its own statement, the Çvetāçvatara Upanishad derives its name from an individual author, and the tradition which attributes it to one of the schools of the Black Yajurveda hardly seems to have a sufficient foundation. Its confused arrangement, the irregularities and arbitrary changes of its metres, the number of interpolated quotations which it contains, make the assumption likely that the work in its present form is not the work of a single author. In its present form it is certainly later than the Kāṭhaka, since it contains several passages which must be referred to that work, besides many stanzas borrowed from it with or without variation. Its lateness is further indicated by the developed theory of Yoga which it contains, besides the more or less definite form in which it exhibits various Vedānta doctrines either unknown to or only foreshadowed in the earlier Upanishads. Among these may be mentioned the destruction of the world by Brahma at the end of a cosmic age (kalpa), as well as its periodic renewal out of Brahma, and especially the explanation of the world as an illusion (māyā) produced by Brahma. At the same time the author shows a strange predilection for the personified forms of Brahma as Savitṛi, Īçāna, or Rudra. Though Çiva has not yet become the name of Rudra, its frequent use as an adjective connected with the latter shows that it is in course of becoming fixed as the proper name of the highest god. In this Upanishad we meet with a number of the terms and fundamental notions of the Sānkhya, though the point of view is thoroughly Vedāntist; matter (prakṛiti), for instance, being represented as an illusion produced by Brahma.
To the White Yajurveda is attached the longest, and, beside the Chhāndogya, 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-kāṇḍa), 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 Yājnavalkya and his two wives in almost identical words throughout. To each of these parts (as well as to Book x. of the Çatapatha Brāhmaṇa) a successive list (vaṃça) of teachers is attached. A comparison of these lists seems to justify the conclusion that the first part (called Madhukāṇḍa) and the second (Yājnavalkya-kāṇḍa) existed during nine generations as independent Upanishads within the school of the White Yajurveda, and were then combined by a teacher named Āgniveçya; 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 (Brāhmaṇas) 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 prāṇa (breath) as a symbol of soul, and then with the creation of the world out of the Ātman 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 Ātman to the gods was still asserting itself. The next chapter deals with the nature of the Ātman and its manifestations, purusha and prāṇa.
The second part of the Upanishad consists of four philosophical discussions, in which Yājnavalkya 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 Yājnavalkya, 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 Ātman can only be described negatively, being intangible, indestructible, independent, immovable.
The third discourse (iv. 3–4) is another dialogue between Janaka and Yājnavalkya. It presents a picture of the soul in the conditions of waking, dreaming, deep sleep, dying, transmigration, and salvation. For wealth of illustration, fervour of conviction, beauty and elevation of thought, this piece is unequalled in the Upanishads or any other work of Indian literature. Its literary effect is heightened by the numerous stanzas with which it is interspersed. These are, however, doubtless later additions. The dreaming soul is thus described:—
Leaving its lower nest in breath’s protection,
And upward from that nest, immortal, soaring,
Where’er it lists it roves about immortal,
The golden-pinioned only swan of spirit (IV. iii. 13).
It roves in dream condition up and downward,