The Upanishads (Sanskrit: उपनिषद्, IAST: Upaniṣad, IPA: [upəniʂəd]) are philosophical texts considered to be an early source from the Hindu religion. They are also called Vedanta, the end of Vedas. In the purest sense, they are not Sruti (of heard). Upanishads explain the essence of vedas. The Upanishads are found mostly in the concluding part of the Brahmanas and in the Aranyakas. All Upanishads have been passed down in oral tradition.

More than 200 are known, of which the first dozen or so, the oldest and most important, are variously referred to as the principal, main (mukhya) or old Upanishads. With the Bhagavad Gita and the Brahmasutra (known collectively as the Prasthanatrayi), the mukhya Upanishads provide a foundation for several later schools of Indian philosophy (vedanta), among them, two influential monistic schools of Hinduism.

Historians believe the chief Upanishads were composed over a wide period ranging from the Pre-Buddhist period to the early centuries BC though minor Upanishads were still being composed in the medieval and early modern period. However, there has been considerable debate among authorities about the exact dating of individual Upanishads. The Upanishads were collectively considered amongst the 100 Most Influential Books Ever Written by the British poet Martin Seymour-Smith. Their significance has been recognized by writers and scholars such as Schopenhauer, Emerson and Thoreau, among others. Scholars also note similarity between the doctrine of Upanishads and those of Plato and Kant

Śri Sathya Sai Baba (born as Sathyanarayana Raju (23 November 1926 – 24 April 2011) was an Indian guru, spiritual figure, mystic, philanthropist and educator. He claimed to be the reincarnation of Sai Baba of Shirdi, considered a spiritual saint and a reputed miracle worker, who died in 1918 and whose teachings were an eclectic blend of Hindu and Muslim beliefs. The materializations of vibhuti (holy ash) and other small objects such as rings, necklaces and watches by Sathya Sai Baba were a source of both fame and controversy; devotees considered them signs of divinity, while skeptics viewed them as simple conjuring tricks. Photos of him are displayed in millions of homes and on the dashboards of cars, and lockets bearing his photo are worn by many as a symbol of good fortune.

Almost everything known about Sathya Sai Baba's early life stems from the hagiography that grew around him, the presentation of narratives that hold special meaning to his devotees and are considered by them evidence of his divine nature. According to his followers, then, Sathyanarayana Raju was born to Easwaramma and Peddavenkama Raju Ratnakaram in the village of Puttaparthi, in what was the Madras Presidency of British India. His birth, which his mother Eswaramma asserted was by miraculous conception, was also said to be heralded by miracles. His siblings included elder brother Ratnam Sesham Raju (1921–1984), sister Venkamma (1923–1993), a second sister Parvathamma (1928–1998), and younger brother Janakiramiah (1930–2003). As a child, he was described as "unusually intelligent" and charitable, though not an exceptional student, as his interests were more of a spiritual nature. He was uncommonly talented in devotional music, dance and drama, and an avid composer of poems and plays. He was said to be capable of materialising objects such as food and sweets out of thin air.

Swāmī Rāma (1925–1996) was born Brij Kiśore Dhasmana or Brij Kiśore Kumar, to a northern Indian Brahmin family in a small village called Toli in the Garhwal Himalayas. From an early age he was raised in the Himalayas by his master Bengali Baba and, under the guidance of his master, traveled from temple to temple and studied with a variety of Himalayan saints and sages, including his grandmaster, who was living in a remote region of Tibet. From 1949 to 1952 he held the prestigious position of Shankaracharya of Karvirpitham (also Karveer Peeth or Karweer Peeth) in South India. After returning to his master in 1952 and practising further for many years in the Himalayan caves, Swami Rama was encouraged by his teacher to go to the West, where he spent a considerable portion of his life teaching, specifically in the United States and Europe.

He is especially notable as one of the first yogis to allow himself to be studied by Western scientists. In the 1960s he allowed himself to be examined by scientists at the Menninger Clinic who studied his ability to voluntarily control bodily processes (such as heartbeat, blood pressure, body temperature, etc.) that are normally considered to be non-voluntary (autonomic).