Upanishads

The Upanishads are Sanskrit texts of the late Vedic and post-Vedic periods that "document the transition from the archaic ritualism of the Veda into new religious ideas and institutions" and the emergence of the central religious concepts of Hinduism. They are the most recent addition to the Vedas, the oldest scriptures of Hinduism, and deal with meditation, philosophy, consciousness, and ontological knowledge. Earlier parts of the Vedas dealt with mantras, benedictions, rituals, ceremonies, and sacrifices.
While among the most important literature in the history of Indian religions and culture, the Upanishads document a wide variety of "rites, incantations, and esoteric knowledge" departing from Vedic ritualism and interpreted in various ways in the later commentarial traditions. The Upanishads are widely known, and their diverse ideas, interpreted in various ways, informed later traditions of Hinduism. The central concern of all Upanishads is to discover the relations between ritual, cosmic realities, and the human body/person, postulating Ātman and Brahman as the "summit of the hierarchically arranged and interconnected universe", but various ideas about the relation between Atman and Brahman can be found.
108 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 Upanishads. The mukhya Upanishads are found mostly in the concluding part of the Brahmanas and Aranyakas and were, for centuries, memorized by each generation and passed down orally. The mukhya Upanishads predate the Common Era, but there is no scholarly consensus on their date, or even on which ones are pre- or post-Buddhist. The Brhadaranyaka is seen as particularly ancient by modern scholars. Of the remainder, 95 Upanishads are part of the Muktikā canon, composed from about the last centuries of 1st-millennium BCE through about 15th-century CE. New Upanishads, beyond the 108 in the Muktika canon, continued to be composed through the early modern and modern era, though often dealing with subjects that are unconnected to the Vedas. The mukhya Upanishads, along with the Bhagavad Gita and the Brahmasutra, are interpreted in divergent ways in the several later schools of Vedanta.
Translations of the Upanishads in the early 19th century started to attract attention from a Western audience. German philosopher Arthur Schopenhauer was deeply impressed by the Upanishads and called them "the most profitable and elevating reading which... is possible in the world." Modern era Indologists have discussed the similarities between the fundamental concepts in the Upanishads and the works of major Western philosophers.

Etymology

The Sanskrit term originally meant “connection” or “equivalence", but came to be understood as "sitting near a teacher," from upa "by" and ni-ṣad "sit down", "sitting down near", referring to the student sitting down near the teacher while receiving spiritual knowledge. Other dictionary meanings include "esoteric doctrine" and "secret doctrine". Monier-Williams' Sanskrit Dictionary notes – "According to native authorities, Upanishad means setting to rest ignorance by revealing the knowledge of the supreme spirit."
Adi Shankaracharya explains in his commentary on the Katha Upanishad| and Brihadaranyaka Upanishad that the word means Ātmavidyā, that is, "knowledge of the self", or Brahmavidyā "knowledge of Brahman". The word appears in the verses of many Upanishads, such as the fourth verse of the 13th volume in the first chapter of the Chandogya Upanishad. Max Müller as well as Paul Deussen translate the word Upanishad in these verses as "secret doctrine", Robert Hume translates it as "mystic meaning", while Patrick Olivelle translates it as "hidden connections".

Development

Authorship

The authorship of most Upanishads is unknown. Sarvapalli 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, 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.

Chronology

Scholars are uncertain about when the Upanishads were composed. The chronology of the early Upanishads is difficult to resolve, states philosopher and Sanskritist Stephen Phillips, because all opinions rest on scanty evidence and analysis of archaism, style and repetitions across texts, and are driven by assumptions about likely evolution of ideas, and presumptions about which philosophy might have influenced which other Indian philosophies. Indologist Patrick Olivelle says that "in spite of claims made by some, in reality, any dating of these documents that attempts a precision closer than a few centuries is as stable as a house of cards".
Some scholars have tried to analyse similarities between Hindu Upanishads and Buddhist literature to establish chronology for the Upanishads. Precise dates are impossible, and most scholars give only broad ranges encompassing various centuries. Gavin Flood states that "the Upanisads are not a homogeneous group of texts. Even the older texts were composed over a wide expanse of time from about 600 to 300 BCE." Stephen Phillips places the early or "principal" Upanishads in the 800 to 300 BCE range.
Patrick Olivelle, a Sanskrit Philologist and Indologist, gives the following chronology for the early Upanishads, also called the Principal Upanishads:

The Brhadaranyaka and the Chandogya are the two earliest Upanishads. They are edited texts, some of whose sources are much older than others. The two texts are pre-Buddhist; they may be placed in the 7th to 6th centuries BCE, give or take a century or so.
The three other early prose Upanishads—Taittiriya, Aitareya, and Kausitaki come next; all are probably pre-Buddhist and can be assigned to the 6th to 5th centuries BCE.
The Kena is the oldest of the verse Upanishads followed by probably the Katha, Isa, Svetasvatara, and Mundaka. All these Upanishads were composed probably in the last few centuries BCE. According to Olivelle, "All exhibit strong theistic tendencies and are probably the earliest literary products of the theistic tradition, whose later literature includes the Bhagavad Gita and the Puranas."
The two late prose Upanishads, the Prasna and the Mandukya, cannot be much older than the beginning of the common era.

Meanwhile, the Indologist Johannes Bronkhorst argues for a later date for the Upanishads than has generally been accepted. Bronkhorst places even the oldest of the Upanishads, such as the Brhadaranyaka as possibly still being composed at "a date close to Katyayana and Patañjali ".
The later Upanishads, numbering about 95, also called minor Upanishads, are dated from the late 1st-millennium BCE to mid 2nd-millennium CE. Gavin Flood dates many of the twenty Yoga Upanishads to be probably from the 100 BCE to 300 CE period. Patrick Olivelle and other scholars date seven of the twenty Sannyasa Upanishads to likely have been complete sometime between the last centuries of the 1st-millennium BCE to 300 CE. About half of the Sannyasa Upanishads were likely composed in 14th- to 15th-century CE.

Geography

The general area of the composition of the early Upanishads is considered as northern India. The region is bounded on the west by the upper Indus valley, on the east by lower Ganges region, on the north by the Himalayan foothills, and on the south by the Vindhya mountain range. Scholars are reasonably sure that the early Upanishads were produced at the geographical center of ancient Brahmanism, Kuru-Panchala, and Kosala-Videha, a "frontier region" of Brahmanism, together with the areas immediately to the south and west of these. This region covers modern Bihar, Nepal, Uttar Pradesh, Uttarakhand, Himachal Pradesh, Haryana, eastern Rajasthan, and northern Madhya Pradesh.
While significant attempts have been made recently to identify the exact locations of the individual Upanishads, the results are tentative. Witzel identifies the center of activity in the Brihadaranyaka Upanishad as the area of Videha, whose king, Janaka, features prominently in the Upanishad. The Chandogya Upanishad was probably composed in a more western than eastern location in the Indian subcontinent, possibly somewhere in the western region of the Kuru-Panchala country.
Compared to the Principal Upanishads, the new Upanishads recorded in the belong to an entirely different region, probably southern India, and are considerably relatively recent. In the fourth chapter of the Kaushitaki Upanishad, a location named Kashi is mentioned.