WIKIPEDIA The Upanishads (Devanagari: ???????, IAST: upani?ad, also spelled “Upanisad”) are Hindu scriptures that constitute the core teachings of Vedanta.[1] They do not belong to any particular period of Sanskrit literature: the oldest, such as the Brhadaranyaka and Chandogya Upanishads, date to the late Brahmana period (around the middle of the first millennium BCE), while the latest were composed in the medieval and early modern period.
upanishad means ‘setting to rest ignorance by revealing the knowledge of the supreme spirit’);…”
Philosophy
The Upanishads speak of a universal spirit (Brahman) and of an individual Self (Atman),[12] and at times assert the identity of both. Brahman is the ultimate, both transcendent and immanent, the absolute infinite existence, the sum total of all that ever is, was, or shall be. The mystical nature and intense philosophical bent of the Upanishads has led to their explication in numerous manners, giving birth to three main schools of Vedanta. Shankara’s exegesis of the Upanishads does not describe Brahman as the God in a monotheistic sense. His philosophy is named advaita, “non-dual” as opposed to dvaita, founded by Madhvacharya, which holds that Brahman is ultimately a personal God, different from the human soul, to be aligned with Vishnu, or Krishna (brahmano hi pratisthaham, I am the Foundation of Brahman Bhagavad Gita 14.27). The third major school of Vedanta, Vishishtadvaita, founded by Ramanujacharya, has aspects in common with both and seeks to reconcile them. The ninth chapter of the Taittiriya Upanishad says: He who knows the Bliss of Brahman (divine consciousness)..does not distress himself with the thought “why did I not do what is good? why did I do what is evil?”. Whoever knows this (bliss) regards both of these as Atman (self, soul), indeed he cherishes both as Atman. Such, indeed, is the Upanishad, the secret knowledge of Brahman. The key phrase of the Upanishads, to Advaita Vedanta, is ??? ?????? ??? “Tat Tvam Asi” (That thou art). Vedantins believe that in the end, the ultimate, formless, inconceivable Brahman is the same as our soul, Atman. We only have to realize this through discrimination. (However, interpretations of this phrase differ.)[13] Verses 6, 7 & 8 of Isha Upanishad: Whoever sees all beings in the soul and the soul in all beings… What delusion or sorrow is there for one who sees unity? It has filled all. It is radiant, incorporeal, invulnerable… Wise, intelligent, encompassing, self-existent, It organizes objects throughout eternity. The Upanishads also contain the first and most definitive explications of the divine syllable Aum or OM, the cosmic vibration that underlies all existence. The mantra “Aum Shanti Shanti Shanti” (the soundless sound, peace, peace, peace)is often found in the Upanishads. ‘Devotion to God’ (Sanskrit: bhakti) is foreshadowed in Upanishadic literature, and was later realized by texts such as the Bhagavad Gita.[14]