Upanishads Part 1 (Sacred books of The East)

The Upanishads (Sanskrit: उपनिषद्, IAST: Upaniṣad, IPA: [upəniʂəd]) are a collection of philosophical texts which form the theoretical basis for the Hindu religion. They are also known as Vedanta ("the end of the Veda"). The Upanishads are considered by Hindus to contain revealed truths (Sruti) concerning the nature of ultimate reality (brahman) and describing the character and form of human salvation (moksha). The Upanishads are found mostly in the concluding part of the Brahmanas and Aranyakas[1] and have been passed down in oral tradition.
More than 200 Upanishads are known, of which the first dozen or so are the oldest and most important and are referred to as the principal or main (mukhya) Upanishads. With the Bhagavad Gita and the Brahmasutra (known collectively as the Prasthanatrayi),[2] the mukhya Upanishads provide a foundation for the several later schools of Vedanta, among them, two influential monistic schools of Hinduism.[note 1][note 2][note 3] The mukhya Upanishads all predate the Common Era, possibly from the Pre-Buddhist period (6th century BCE) [6][7] down to the Maurya period.[7] The remainder of the Muktika canon was mostly composed during medieval Hinduism, and new Upanishads continued being composed in the early modern and modern era,[8] down to at least the 20th century.
The significance of Upanishads has been recognized by writers and scholars such as Schopenhauer, Emerson, Thoreau, and others. Scholars also note similarity between the doctrine of Upanishads and those of Plato and Kant [9][10] The Upanishads were collectively considered among the 100 Most Influential Books Ever Written by the British poet Martin Seymour-Smith.[11] Some criticism of the Upanishads revolves around the denial of pluralistic ideas due to the core philosophy of unity of the Upanishads. On the contrary, the exponents of Upanishadic philosophy assert that the Upanishads are not merely denying the apparent plurality but rather claiming that the human mind has the ability to realize quintessential unity behind all plurality and experience life based on this realization, and a movement toward such a realization is necessary to produce a healthier individual and a healthier society. The unity propounded by Upanishadic seers is often compared to the unity of laws of physics discovered by the physicists and the unity of the living matter on earth as discovered by the later biologists.