Upanishads (उपनिषदः)

Upanishads (Samskrit : उपनिषद्) are the concluding segments, available as a part of Aranyakas. Since they expound the various spiritual and dharmika siddhantas and tattvas that leads a sadhaka to the highest purpose of Moksha and because they are present at the end of the Vedas, they are also referred to as the Vedanta. They do not forbid the rituals or rites prescribed in the Karmakanda but expound that only through Jnana one can attain moksha.

वेदान्तो नामोपनिषत्प्रमाणं तदनुसारीणि। शारीरकसूत्राणि च ।

Sadananda Yogindra, in his Vedantasara says that "Vedanta has the Upanishads for its evidence and includes the Sharira Sutras and other works which corroborate it"

The word Vedanta is a compound word made up of two Sanskrit words: ‘Veda’ and  ‘Anta’. The word ‘anta’ means an end. The Vedanta includes the class of writings under the heading Prasthana Trayi, namely The Upanishads, Brahmasutras and Bhagavadgita. It essentially refers to the philosophy pronounced in the Upanishads, the final parts of the Vedas.

परिचयः ॥ Introduction

The Vedas have been divided into four styles of texts – the Samhitas, the Aranyakas, the Brahmanas and the Upanishads. The subject matter of the whole Veda is divided into Karma-Kanda, Upasana-Kanda and Jnana-Kanda. The Karma-Kanda or Ritualistic section deals with various sacrifices and rituals. The Upasana-Kanda or Worship section deals with various kinds of worship or meditation. The Jnana-Kanda or Knowledge-Section deals with the highest knowledge of Nirguna Brahman. The Samhitas and the Brahmanas constitute Karma-Kanda; the Aranyakas constitute Upasana-Kanda; and the Upanishads constitute Jnana-KandaThe Upanishads along with the Bhagavadgita and Brahmasutras constitute the Prasthana Trayi (प्रस्थानत्रयी) and both the Gita and Brahmasutras are based again on the Upanishads. They are also the foundational sources for all Darshana shastras and including the Jain and Buddhist philosophies.

According to Dr. K. S. Narayanacharya, these are four different modes of expressing the same truths, each as a cross check against others so that misrepresentations are avoided, a method used and valid even today.

Most of the Upanishads are in forms of dialogues between a master and a disciple. In Upanishads, a seeker raises a topic and the enlightened guru satisfies the query aptly and convincingly. The central concepts found in the Upanishads involve the following aspects of Sanatana Dharma

• Brahman (Supreme Being, Ultimate Reality)
• Ātman (Self)
• Jiva (Embodiment of Atman)
• Unity of Brahman and Atman (Know that you are Ātman)
• Srshti (Origin of Creation)
• Jnana (Knowledge that Unity and Self are not separate)
• Avidya (Ignorance)
• Moksha (The Paramapurushartha)

The Upanishads speak about the identity of the Supreme Being, the Brahman, the individual Atman, their mutual relationship, the Universe (jagat) and man’s place in it. In short they deal with Jiva, Jagat and Jagadishwara and ultimately the path to mokṣa or mukti. Chronology and dating of Upanishads is not attempted in this article.

व्युत्पत्तिः ॥ Etymology

There are different versions about the meaning of Upanishad as given by many scholars. The term Upaniṣad term consists of उप (upa) and नि (ni) उपसर्ग-s (Upasargas or Prefixes) and सद् धातुः (Sad dhatu) followed by किव्प् प्रत्ययः (Kvip pratyaya as Suffix) used in the sense of विशरणगत्यवसादनेषु । Shri Adi Shankaracharya explains in his commentary on Taittriyopanishad about the meanings of Sad dhatu thus

• विशरण (नाशनम्) to destroy : They destroy the seeds of Avidya causing samsara in a Mumukshu (a sadhaka who wants to attain Moksha), hence this Vidya is called Upanishads

  अविद्यादेः संसारबीजस्य विशरणाद् विनाशनादित्यनेन अर्थयोगेन विद्या उपनिषदुच्यते । avidyādeḥ saṁsārabījasya viśaraṇād vināśanādityanena arthayogena vidyā upaniṣaducyate ।

• गति (प्रपणम् वा विद्यर्थकम्) to obtain or to know : That vidya which leads to or make the sadhaka obtain Brahma, is called Upanishad.

  परं ब्रह्म वा गमयतोति ब्रह्म गमयितृत्वेन योगाद् विद्योपनिषद् । paraṁ brahma vā gamayatoti brahma gamayitr̥tvena yogād vidyopaniṣad ।

• अवसादन (शिथिलर्थकम्) to loosen or to dissolve : Through which cycles of birth, aging etc painful process are loosened or dissolved (that is bondages of samsara are dissolved allowing the sadhaka to attain the Brahma)

  गर्भवासजन्मजराद्युपद्रववृन्दस्य लोकान्तरेपौनपुन्येन प्रवृत्तस्य अवसादपितृत्वेन उपनिषदित्युच्यते । garbhavāsajanmajarādyupadravavr̥ndasya lokāntarepaunapunyena pravr̥ttasya avasādapitr̥tvena upaniṣadityucyate ।

  His also defines the primary meaning of Upanishad as ब्रह्मविद्या (Brahmavidya। Knowledge of Brahma) and secondary meaning as ब्रह्मविद्याप्रतिपादकग्रन्थः (Brahmavidya pratipadaka granth । texts which teach Brahmavidya). Shankaracharya's commentaries of the Kaṭha and Brihadaranyaka Upanishad also support this explanation.

An alternative explanation of the word Upanishad is "to sit near" derived as follows

• नि (ni) उपसर्ग (Upasarga or Prefix) in front of सद् धातुः (Sad dhatu) also means 'to sit'.
• उप (upa) Upasarga is used to mean 'nearness or close to'.
• उपनिषद् term thus means "to sit near"

Thus Upanishad came to mean as ' to sit near the Guru (preceptor) to obtain the 'secret knowledge' or Brahmavidya (as per Shabdakalpadhruma : उपनिषद्यते प्राप्यते ब्रह्म-विद्या अनया इति)

Generally, Upanishads are synonymous with Rahasya (रहस्यम्) or secrecy. Upanishads themselves mention statements such as "इति उपनिषद् इति रहस्यम्" when discussing some important siddhantas. Probably such usages are given to prevent and caution against giving this knowledge to the undeserving.

In the mukhya upanishads, there are many instances of रहस्यम् meaning secret or hidden knowledge especially in Atharvaveda upanishads. Kaushitaki Upanishad for example, contains detailed siddhantas of मनोज्ञानम् and तत्वज्ञानम् (Psychology and metaphysics). Apart from them they also contain मृतकज्ञानम् (siddhantas around death, travel of Atman etc), बालमृत्यु निवारणम् (preventing untimely childhood deaths) शत्रुविनाशार्थ रहस्यम् (secrets about the destruction of enemies) etc. Chandogya Upanishads gives the secrets about the origin of worlds, Jiva, Jagat, Om and their hidden meanings.

Classification of Upanishads

More than 200 Upanishads are known, of which the first dozen or so are the oldest (प्राचीनम्), most important and are referred to as the principal or main (mukhya) Upanishads. The rest of them aid in explaining bhakti or jnana concepts and many are without bhashyas. Some scholars accept 12 Upanishads and some even consider 13 to be the principal Upanishads and some others accept 108 Upanishads given by Muktikopanishad.

There is no fixed list of the Upanishads as newer ones, beyond the Muktika Upanishad list of 108 Upanishads, have continued to be discovered and composed. A collection of Upanishads, namely Upanishad Samgrahah by Pt. J. K. Shastri contains 188 upanishads. Pracheena Upanishads have long been revered in Sanatana Dharma traditions, and many sampradayas have interpreted the concepts of Upanishads to evolve their sampradaya. These "new Upanishads" number in the hundreds, cover diverse range of topics from physiology to renunciation.

Basis for Classification

Many modern and western indology thinkers have put forth their contemplations on the classification of Upanishads based on

1. the presence or absence of Shankaracharya's bhasyas (Ten for which bhashyas are available are Dasopanishads and the rest describing devatas. Vaishnava, Shaiva, Shakta, Saurya etc)
2. the ancientness of Upanishad based on association with Aranyakas and Brahmanas
3. the ancientness and modernness of the Upanishads based on description of deities and other aspects ( Given by Shri Chintamani Vinayak on Page 256 of Reference )
4. the shanti patha given in each of the Upanishads
5. the ancientness and modernness of the Upanishads having prose or metrical compositions (mostly given by Western Indologists like Dr. Daison)

दशोपनिषदः ॥ Dasopanishads

Muktikopanishad lists the following ten as principal Upanishads which have received attention from Shri Adi Shankaracharya in form of his bhasyas and are considered ancient (प्राचीनम्).

ईश-केन-कठ-प्रश्न-मुण्ड-माण्डूक्य-तित्तिरः । एेतरेयं च छान्दोग्यं बृहदारण्यकं तथा ॥ īśa-kēna-kaṭha-praśna-muṇḍa-māṇḍūkya-tittiraḥ । ēētarēyaṁ ca chāndōgyaṁ br̥hadāraṇyakaṁ tathā ॥

The 10 Mukhya Upanishad on which Adi Shankaracharya commented are:

1. ईशावाश्योपनिषद् ॥ Ishavasya Upanishad (Shukla Yajur Veda)
2. केनोपनिषद् ॥ Kena Upanishad (Sama Veda)
3. कठोपनिषद् ॥ Katha Upanishad (Yajur Veda)
4. प्रश्नोपनिषद् ॥ Prashna Upanishad (Atharva Veda)
5. मुण्डकोपनिषद् ॥ Mundaka Upanishad (Atharva Veda)
6. माण्डूक्योपनिषद् ॥ Mandukya Upanishad (Atharva Veda)
7. तैत्तियोपनिषद् ॥ Taittiriya Upanishad (Yajur Veda)
8. एेतरेयोपनिषद् ॥ Aitareya Upanishad (Rig Veda)
9. छान्दोग्योपनिषद्॥ Chhandogya Upanishad (Sama Veda)
10. बृहदारण्यकोपनिषद् Brhadaranyaka Upanishad (Yajur Veda)

Apart from these ten, कौषीतकि (Kaushitaki) श्वेताश्वतर (Shvetasvatara) and मैत्रायणीय (Maitrayaniya) Upanishads are regarded as ancient since the first two of these three found a mention by Shankaracharya in his Brahmasutra bhashyas along with dashopanishad bhashyas. However, there are no available commentaries on these given by him.

Upanishads as Part of Aranyakas

Many Upanishads are the final or exclusive portions of the Aranyakas or the Brahmanas. But these refer mainly to the dasha upanishads. It may be seen from the table below that some Upanishads not classified in dashopanishads are from Aranyakas. (Ex: Mahanarayaneeya Upanishad, Maitrayaniya Upanishad) while the Atharvana veda associated Upanishads do not have corresponding Brahmanas or Aranyakas as they are unavailable.

Upanishads as part of Aranyakas and Brahmanas

Veda		What part of Brahmana or Aranyaka constitutes Upanishad	Name of Upanishad
RigVeda		4th to 6th Adhyayas of 2nd Prapathaka of 2nd Aranyaka of Aitareya Aranyaka (Page 250 of Reference )	एेतरेयोपनिषद् ॥ Aitareya Upanishad
		3rd to 6th Adhyayas of Shankhyayana Aranyaka (Page 251 of Reference )	कौषीतकि उपनिषद् ॥ Kaushitaki Upanishad
Yajurveda	Krishna	7th to 9th Prapathakas of Taittriya Aranyaka (Page 251 of Reference )	तैत्तियोपनिषद् ॥ Taittiriya Upanishad
		10th Prapathaka of Taittriya Aranyaka (also considered as Khila khanda) (Page 251 of Reference )	महानारायणीय उपनिषद् ॥ Mahanarayaneeya Upanishad
		Kathasamhita or Kathavalli (Page 54 of Reference )	कठोपनिषद् ॥ Katha Upanishad
		Maitrayaniya Aranyaka (Page 251 of Reference )	मैत्रायणीय Maitrayaniya Upanishad
	Shukla	Last 6 Adhyayas of Shatapatha Brahmana (Page 56 of Reference )	Brhadaranyakopanishad
		40th Adhyaya of माध्यन्दिन-शतपथ-ब्राह्मणम् ॥ Madhyandina Shatapatabrahmana	ईशावाश्योपनिषद् ॥ Ishavasya Upanishad
Samaveda		10th Anuvaka of 4th Adhyaya of जैमिनीय ॥ Jaiminiya (Talavakara तलवकार) Brahmana (Page 253 of Reference )	केनोपनिषद् ॥ Kena Upanishad
		Last 10 Adhyayas of Chandogyabrahmana of Kauthuma Shakha (Page 55 of Reference )	छान्दोग्योपनिषद्॥ Chhandogya Upanishad
Adharvaveda		Associated with Pippalada brahmana (Page 54 of Reference )	प्रश्नोपनिषद् ॥ Prashna Upanishad
		Associated with Shaunaka samhita (Page 54 of Reference )	मुण्डकोपनिषद् ॥ Mundaka Upanishad
		Associated with Atharvaveda (Page 55 of Reference )	माण्डूक्योपनिषद् ॥ Mandukya Upanishad

Deity and Samkhya Based Classification

Pt. Shri. Chintamani Vinayak Vaidya has assigned the ancientness (प्राचीनता) or modernness (अर्वाचीनता) of Upanishads using the two factors

1. Siddhanta of Anatmarupa Brahma (a supreme power beyond and above deities)
2. Vishnu or Shiva deities are accepted as paradevata (supreme deity) and are praised
3. Principles of Samkhya Siddhanta (Prakriti, Purusha, Gunas-Satva, Rajas and Tamas)

It is proved beyond doubt that the ancient upanishads have described a Supreme Anatmarupa Brahma, above the vaidika deities, who has created regulated and maintained order of the creation. They are thus very ancient and include Aitareya, Isha, Taittriya, Brhadaranyaka, Chandogya, Prashna, Mundaka and Mandukya Upanishads.

Only in the more recent upanishads one can see the older ones in praise of Vishnu as the Supreme Being followed by the more recent one's in praise of Shiva. In this group is classified Kathopanishad where Vishnu is the Supreme Being. Krishna Yajurveda Upanishads are famous for their Shiva and Rudra stutis (Rudra Prashna is a famous stuti) and in this way Shevetashvatara Upanishad which accepts Shiva as paradevata is more recent compared to Kathopanishad. In this series, Maitrayaniya Upanishad which accepts all the Trimurti's (Brahma Vishnu and Shiva) is more recent than the above two mentioned Upanishads.

Katha Upanishad (which has no principles of Samkhya) is ancient as against Shvetashvatara (which expounds principles of Samkhya and its preceptor Kapila Maharshi), further more recent is Maitrayaniya Upanishad where samkhya philosophy along with the description of the gunas is given in detail.

Shanti Patha Based Classification

Some upanishads are not related to any veda, while some are definitely associated with one or the other veda. Based on the Shanti patha that is given in the beginning of the Upanishads the following classification is proposed.(Page 288-289 of Reference )

108 Upanishads Classified Based on Shanti Patha of Each Veda

Veda	Shanti patha	Upanishads
Rigveda	Vangmemanasi...	Aitareya, Kaushitaki, Atmaprabodha, Nadabindu, Nirvana, Mudgala, Akshamalika, Tripura, Saubhagya, Bahvrucha Upanishads (10)
Krishna Yajurveda	Sahanavavatu...	Kathavalli (commonly referred to as Kathopanishad), Taittriya, Narayana, Brahma, Kaivalya, Shvetasvatara, Garbha, Amrtabindu, Amrtanada, Kalagnirudra, Kshurika, Sarvasara, Shukarahasya, Tejobindu, Dhyanabindu, Brahmavidya, Yogatattva, Dakshinamurty, Katha (different from Kathavalli), Skanda, Shareeraka, Varaha, Yogashikha, Ekakshara, Akshi, Avadhuta, Rudrahrdaya, Yogakundalini, Panchabrahma, Kalisantarana, Pranagnihotra, Sarasvatirahasya Upanishads (32)
Shukla Yajurveda	Purnamadah Purnamida ...	Ishavasya, Brhadaranya, Jabala, Subaala, Hamsa, Paramahamsa, Mantrikaniralamba, Tarasara, Trishikhi, Brahmanamandala, Brahmana, Advayataraka, Paingala, Bhikshuka, Turiyateeta, Adhyatma, Muktika, Shatyayani, Yajnavalkya Upanishads (19)
Samaveda	Apyayantu...	Kena, Chandogya, Aaruni, Maitrayani, Maitreyi, Vajrasuchi, Yoga, Chudamani, Vasudeva, Sanyasa, Avyakta, Savitri, Rudrakshajabala, Darshanajabali, Kundika, Mahopanishad Upanishads (16)
Adharvanaveda	Bhadramkarnebhi...	Prashna, Mundaka, Mandukya, Brhadjabala, Nrsimhatapini, Narada parivrajaka, Sitaa, Sharabha, Mahanarayana, Ramarahasya, Ramatapini, Shandilya, Paramahamsa parivrajaka, Annapurna, Surya, Atma, Parambrahma, Pashupata, Tripuratapini, Devi, Bhavana, Bhasmajabala, Ganapati, Mahavakya, Gopalatapini, Krishna, Hayagriva, Garuda, Dattatreya, Atharvashikha, Atharvashiro Upanishads (31)

Authorship

The authorship of most Upanishads is uncertain and unknown. The various philosophical theories in the early Upanishads have been attributed to famous seers such as Yajnavalkya, Uddalaka Aruni, Shvetaketu, Shandilya, Aitareya, Balaki, Pippalada and Sanatkumara. Women, such as Maitreyi and Gargi participated in the dialogues and are also credited in the early Upanishads.

There are exceptions to the anonymous tradition of the Upanishads and other Vedic literature. The Shvetashvatara Upanishad, for example, includes closing credits to Shvetashvatara, and he is considered the author of the Upanishad.

Upanishad vishaya

The main concept of Upanishads is the discussion about Paramatmatattva. There are two kinds of Vidyas : Para and Apara. Of these Paravidya is supreme and is called Brahmavidya. Upanishads present the detailed discussion about Paravidya. Aparavidya is primarily related to Karmas, hence called Karmavidya. The fruits of Karmavidya are perishable while the results of Brahmavidya are indestructable. Aparavidya may not lead one to Moksha (may lead to svarga and other worlds) but Paravidya always gives Moksha.

Some terms which are well explained in the Upanishads include, Prkriti, Purusha, Paramatma, Ishvara, Jivatma, Maya, Brahman, Avidya, Indriyas, etc. From the root cause Prkriti the world came into being. Paramatma is Nitya, Puratana, Shasvata (Eternal) devoid of the cycles of birth and death. The Sharira or body is subjected to death and birth but Atma residing in it continues to exist. Just like butter is evenly distributed in milk so also Paramatma is all-pervading in the world. Just like the sparks arise out of fire so also the beings take shape from the Paramatma. Such aspects which are explained in Upanishads have widely developed in the Darshana shastras.

Based on their content Upanishads can be divided into six categories.

1. Vedanta siddhanta
2. Yoga siddhanta
3. Samkhya siddhanta
4. Vaishnava siddhanta
5. Shaiva siddhanta
6. Shakta siddhanta

Special Points

Although all Upanishads proclaim that the goal of human life, embroiled in the flow of samsara, is to attain Jnana that leads to Moksha, the ultimate paramapurushartha, each of the upanishads have their own special features about their siddhantas as follows

1. Katha discusses the doubts about post death path of a Jiva
2. Shvetasvatara says Jagat and Paramatma are Maya
3. Brhadaranyaka gives the paths to higher worlds
4. Mundakopanishad stressed the fact that the whole Universe is nothing but Parabrahma
5. Isavasya defines that a Jnani is one who sees Self and Paramatma pervading the world.
6. Taittriyopanishad proclaims that Brahmajnana leads to Moksha.
7. Chandogyopanishad gives the outline of how janmas (births) happen and paths to reach Brahmaloka.
8. Prashnopanishad logically answers the questions regarding the nature of Atma.
9. Mandukya upanishad proclaims Atman to be Brahman
10. Aitareya upanishad establishes the characteristics of Brahma

The Upanishadic age was characterized by a pluralism of worldviews. While some Upanishads have been deemed 'monistic', others, including the Katha Upanishad, are dualistic.^[74] The Maitri is one of the Upanishads that inclines more toward dualism, thus grounding classical Samkhya and Yoga schools of Hinduism, in contrast to the non-dualistic Upanishads at the foundation of its Vedanta school.^[75] They contain a plurality of ideas.^{[76][note 8]}

The Upanishads include sections on philosophical theories that have been at the foundation of Indian traditions. For example, the Chandogya Upanishad includes one of the earliest known declaration of Ahimsa (non-violence) as an ethical precept.^[39][40] Discussion of other ethical premises such as Damah (temperance, self-restraint), Satya (truthfulness), Dāna (charity), Ārjava (non-hypocrisy), Daya (compassion) and others are found in the oldest Upanishads and many later Upanishads.^[41][42] Similarly, the Karma doctrine is presented in the Brihadaranyaka Upanishad, which is the oldest Upanishad.^[43]

Development of thought

While the hymns of the Vedas emphasize rituals and the Brahmanas serve as a liturgical manual for those Vedic rituals, the spirit of the Upanishads is inherently opposed to ritual.^[86] The older Upanishads launch attacks of increasing intensity on the ritual. Anyone who worships a divinity other than the Self is called a domestic animal of the gods in the Brihadaranyaka Upanishad. The Chāndogya Upanishad parodies those who indulge in the acts of sacrifice by comparing them with a procession of dogs chanting Om! Let's eat. Om! Let's drink.^[86]

The Kaushitaki Upanishad asserts that "external rituals such as Agnihotram offered in the morning and in the evening, must be replaced with inner Agnihotram, the ritual of introspection", and that "not rituals, but knowledge should be one's pursuit".^[44] The Mundaka Upanishad declares how man has been called upon, promised benefits for, scared unto and misled into performing sacrifices, oblations and pious works.^[45] Mundaka thereafter asserts this is foolish and frail, by those who encourage it and those who follow it, because it makes no difference to man's current life and after-life, it is like blind men leading the blind, it is a mark of conceit and vain knowledge, ignorant inertia like that of children, a futile useless practice.^[45][46] The Maitri Upanishad states,^[47]

The performance of all the sacrifices, described in the Maitrayana-Brahmana, is to lead up in the end to a knowledge of Brahman, to prepare a man for meditation. Therefore, let such man, after he has laid those fires,^[91] meditate on the Self, to become complete and perfect.

— Maitri Upanishad^[92][93]

The opposition to the ritual is not explicit in the oldest Upanishads. On occasions, the Upanishads extend the task of the Aranyakas by making the ritual allegorical and giving it a philosophical meaning. For example, the Brihadaranyaka interprets the practice of horse-sacrifice or ashvamedha allegorically. It states that the over-lordship of the earth may be acquired by sacrificing a horse. It then goes on to say that spiritual autonomy can only be achieved by renouncing the universe which is conceived in the image of a horse.^[86]

In similar fashion, Vedic gods such as the Agni, Aditya, Indra, Rudra, Visnu, Brahma and others become equated in the Upanishads to the supreme, immortal and incorporeal Brahman-Atman of the Upanishads, god becomes synonymous with Self, and is declared to be everywhere, inmost being of each human being and within every living creature.^[48][49][50] The one reality or ekam sat of the Vedas becomes the ekam eva advitiyam or "the one and only and sans a second" in the Upanishads.^[86] Brahman-Atman and Self-realization develops, in the Upanishad, as the means to moksha (liberation, freedom in this life or after-life).^[50][51][52]

Brahman and Atman

Main articles: Ātman (Hinduism) and Brahman

Two concepts that are of paramount importance in the Upanishads are Brahman and Atman.^[101] The Brahman is the ultimate reality and the Atman is individual self (soul).^[53][54] Brahman is the material, efficient, formal and final cause of all that exists.^[55][56][57] It is the pervasive, genderless, infinite, eternal truth and bliss which does not change, yet is the cause of all changes.^[53][58] Brahman is "the infinite source, fabric, core and destiny of all existence, both manifested and unmanifested, the formless infinite substratum and from which the universe has grown". Brahman in Hinduism, states Paul Deussen, as the "creative principle which lies realized in the whole world".^[59]

The word Atman means the inner self, the soul, the immortal spirit in an individual, and all living beings including animals and trees.^[60][54] Ātman is a central idea in all the Upanishads, and "Know your Ātman" their thematic focus.^[61] These texts state that the inmost core of every person is not the body, nor the mind, nor the ego, but Atman – "Soul" or "Self".^[62] Atman is the spiritual essence in all creatures, their real innermost essential being.^[63][64] It is eternal, it is ageless. Atman is that which one is at the deepest level of one's existence.

Atman is the predominantly discussed topic in the Upanishads, but they express two distinct, somewhat divergent themes. Some state that Brahman (Highest Reality, Universal Principle, Being-Consciousness-Bliss) is identical with Atman, while others state Atman is part of Brahman but not identical.^[65][66] This ancient debate flowered into various dual, non-dual theories in Hinduism. The Brahmasutra by Badarayana (~ 100 BCE) synthesized and unified these somewhat conflicting theories, stating that Atman and Brahman are different in some respects particularly during the state of ignorance, but at the deepest level and in the state of Self-realization, Atman and Brahman are identical, non-different.^[65]

The idea put forth by the Upanishadic seers that Atman and Brahman are One and the same is one of the greatest contributions made to the thought of the world.^{[116][117][118][119]}

Illusion

Main article: Maya (illusion)

Two different types of the non-dual Brahman-Atman are presented in the Upanishads, according to Mahadevan.^[120] The one in which the non-dual Brahman-Atman is the all inclusive ground of the universe and another in which empirical, changing universe is a form of Maya, often translated as "illusion".

The Upanishads describe the universe, and the human experience, as an interplay of Purusha (the eternal, unchanging principles, consciousness) and Prakṛti (the temporary, changing material world, nature).^[67] The former manifests itself as Ātman (Soul, Self), and the latter as Māyā. The Upanishads refer to the knowledge of Atman as "true knowledge" (Vidya), and the knowledge of Maya as "not true knowledge" (Avidya, Nescience, lack of awareness, lack of true knowledge).^[68]

Hendrick Vroom explains, "the term Maya [in the Upanishads] has been translated as 'illusion,' but then it does not concern normal illusion. Here 'illusion' does not mean that the world is not real and simply a figment of the human imagination. Maya means that the world is not as it seems; the world that one experiences is misleading as far as its true nature is concerned."^[69] According to Wendy Doniger, "to say that the universe is an illusion (māyā) is not to say that it is unreal; it is to say, instead, that it is not what it seems to be, that it is something constantly being made. Māyā not only deceives people about the things they think they know; more basically, it limits their knowledge."^[70]

In the Upanishads, Māyā is the perceived changing reality and it co-exists with Brahman which is the hidden true reality.^[71][72] Maya, or "illusion", is an important idea in the Upanishads, because the texts assert that in the human pursuit of blissful and liberating Self-knowledge, it is Maya which obscures, confuses and distracts an individual.^[73][74]

Schools of Vedanta

Main article: Vedanta

The Upanishads form one of the three main sources for all schools of Vedanta, together with the Bhagavad Gita and the Brahmasutras.^[129] Due to the wide variety of philosophical teachings contained in the Upanishads, various interpretations could be grounded on the Upanishads. The schools of Vedānta seek to answer questions about the relation between atman and Brahman, and the relation between Brahman and the world.^[130] The schools of Vedanta are named after the relation they see between atman and Brahman:^[131]

• According to Advaita Vedanta, there is no difference.^[131]
• According to Vishishtadvaita the jīvātman is a part of Brahman, and hence is similar, but not identical.
• According to Dvaita, all individual souls (jīvātmans) and matter as eternal and mutually separate entities.

Other schools of Vedanta include Nimbarka's Dvaitadvaita, Vallabha's Suddhadvaita and Chaitanya's Acintya Bhedabheda.^[132] The philosopher Adi Sankara has provided commentaries on 11 mukhya Upanishads.^[133]

Advaita Vedanta

Advaita literally means non-duality, and it is a monistic system of thought.^[134] It deals with the non-dual nature of Brahman and Atman. Advaita is considered the most influential sub-school of the Vedanta school of Hindu philosophy.^[134] Gaudapada was the first person to expound the basic principles of the Advaita philosophy in a commentary on the conflicting statements of the Upanishads.^[135] Gaudapada's Advaita ideas were further developed by Shankara.^[136][137] King states that Gaudapada's main work, Māṇḍukya Kārikā, is infused with philosophical terminology of Buddhism, and uses Buddhist arguments and analogies.^[138] King also suggests that there are clear differences between Shankara's writings and the Brahmasutra,^[136][137] and many ideas of Shankara are at odds with those in the Upanishads.^[139] Radhakrishnan, on the other hand, suggests that Shankara's views of Advaita were straightforward developments of the Upanishads and the Brahmasutra,^[140] and many ideas of Shankara derive from the Upanishads.^[75]

Shankara in his discussions of the Advaita Vedanta philosophy referred to the early Upanishads to explain the key difference between Hinduism and Buddhism, stating that Hinduism asserts "Atman (Soul, Self) exists", while Buddhism asserts that there is "no Soul, no Self".^[76][77][78]

The Upanishads contain four sentences, the Mahāvākyas (Great Sayings), which were used by Shankara to establish the identity of Atman and Brahman as scriptural truth:

• "Prajñānam brahma" - "Consciousness is Brahman" (Aitareya Upanishad)^[145]
• "Aham brahmāsmi" - "I am Brahman" (Brihadaranyaka Upanishad)^[146]
• "Tat tvam asi" - "That Thou art" (Chandogya Upanishad)^[147]
• "Ayamātmā brahma" - "This Atman is Brahman" (Mandukya Upanishad)^[148]

Although there are a wide variety of philosophical positions propounded in the Upanishads, commentators since Adi Shankara have usually followed him in seeing idealist monism as the dominant force.^{[149][note 9]}

Dvaita

The Dvaita school was founded by Madhvacharya.^[150] Dvaita is regarded as the best philosophic exposition of theism.^[151] Madhva, much like Adi Shankara claims for Advaita, states that his theistic Dvaita Vedanta is grounded in the Upanishads.^[79]

Vishishtadvaita

The third school of Vedanta is the Vishishtadvaita, which was founded by Ramanuja. Ramanuja strenuously refuted Shankara's works.^[153] Visistadvaita is a synthetic philosophy bridging the monistic Advaita and theistic Dvaita systems of Vedanta.^[151] Ramanuja, just as Madhva claims for Dvaita sub-school, states that Vishishtadvaita is grounded in the Upanishads.^[79]

Isha Kena Katha Prashna Mundaka Mandukya Taittiriya Aitareya Chandogya Brihadaranyaka Brahma Kaivalya Jabala Shvetashvatara Hamsa Aruneya Garbha Narayana Paramahamsa Amritabindu Amritanada Atharvashiras Atharvashikha Maitrayaniya Kaushitaki Brihajjabala Nrisimha Tapaniya Kalagni Rudra Maitreya Subala Kshurika Mantrika Sarvasara Niralamba Shukarahasya Vajrasuchi Tejobindu Nadabindu Dhyanabindu Brahmavidya Yogatattva Atmabodha Naradaparivrajaka Trishikhi-brahmana Sita Yogachudamani Nirvana Mandala-brahmana Dakshinamurti Sharabha Skanda Mahanarayana Advayataraka Rama Rahasya Ramatapaniya Vasudeva Mudgala Shandilya Paingala Bhikshuka Maha Sariraka Yogashikha Turiyatita Sannyasa Paramahamsaparivrajaka Akshamalika Avyakta Ekakshara Annapurna Surya Akshi Adhyatma Kundika Savitri Atma Pashupatabrahma Parabrahma Avadhuta Tripuratapini Devi Tripura Kathashruti Bhavana Rudrahridaya Yoga-Kundalini Bhasma Rudraksha Ganapati Darshana Tarasara Mahavakya Pancabrahma Pranagnihotra Gopala-Tapani Krishna Yajnavalkya Varaha Shatyayaniya Hayagriva Dattatreya Garuda Kali-Santarana Jabali Saubhagyalakshmi Sarasvati-rahasya Bahvricha Muktikā