linguistic:paraphrasing
Authorship

The authorship of most Upanishads is unknown. Radhakrishnan states, "almost all the early literature of India was anonymous, we do not know the names of the authors of the Upanishads". The ancient Upanishads are embedded in the Vedas, the oldest of Hinduism's religious scriptures, which some traditionally consider to be apauruṣeya, which means "not of a man, superhuman" and "impersonal, authorless". The Vedic texts assert that they were skillfully created by Rishis (sages), after inspired creativity, just as a carpenter builds a chariot.

The various philosophical theories in the early Upanishads have been attributed to famous sages such as Yajnavalkya, Uddalaka Aruni, Shvetaketu, Shandilya, Aitareya, Balaki, Pippalada, and Sanatkumara. Women, such as Maitreyi and Gargi, participate in the dialogues and are also credited in the early Upanishads. There are some exceptions to the anonymous tradition of the Upanishads. The Shvetashvatara Upanishad, for example, includes closing credits to sage Shvetashvatara, and he is considered the author of the Upanishad.

Many scholars believe that early Upanishads were interpolated and expanded over time. There are differences within manuscripts of the same Upanishad discovered in different parts of South Asia, differences in non-Sanskrit version of the texts that have survived, and differences within each text in terms of meter, style, grammar and structure. The existing texts are believed to be the work of many authors.