Ādi Shankara

Adi Shankara (8th c. CE), also called Adi Shankaracharya (, ), was an Indian Vedic scholar-monk, philosopher, and teacher (acharya) of Advaita Vedanta. He wrote influential commentaries on the Brahma sutras and other texts, and in recent times is often revered as the most important Indian philosopher. Reliable information on Shankara's actual life is scant, and the historical influence of his works on Hindu intellectual thought has been questioned. The historical Shankara was probably relatively unknown and Vaishnava-oriented and his true impact lies in the popular perception of him as a heroic religious leader who re-established traditional Hinduism.

Until the 10th century Shankara was overshadowed by his older contemporary Maṇḍana Miśra, and there is no mention of him in concurrent Hindu, Buddhist or Jain sources until the 11th century. The legendary Shankara was created in the 14th century, centuries after his death, when Sringeri maṭha (monastery, temple-school) started to receive patronage from the emperors of the Vijayanagara Empire and shifted their allegiance from Advaitic Agamic Shaivism to Brahmanical Advaita orthodoxy. Hagiographies dating from the 14th-17th centuries deified him as a ruler-renunciate, travelling on a digvijaya (conquest of the four quarters) across the Indian subcontinent to propagate his philosophy, defeating his opponents in theological debates. These hagiographies also portray him as founding four mathas. Adi Shankara also came to be regarded as the organiser of the Dashanami monastic order, and the unifier of the Shanmata tradition of worship. The title of Shankaracharya, used by heads of certain monasteries in India, is derived from his name. Tradition also portrays him as the one who reconciled the various sects (Vaishnavism, Shaivism, and Shaktism) with the introduction of the form of worship, the simultaneous worship of five deities – Ganesha, Surya, Vishnu, Shiva, and Devi, arguing that all deities were but different forms of the one Brahman, the invisible Supreme Being.

Owing to his later fame over 300 texts are attributed to him, including commentaries (bhāṣya), introductory topical expositions (prakaraṇa grantha) and poetry (stotra). However, most of these are likely to have been written by admirers, or pretenders, or scholars with an eponymous name. Works wideli accepted to have been written by Shankara himself are the Brahmasutrabhasya, his commentaries on ten principal Upanishads, his commentary on the Bhagavad Gita, and the Upadeśasāhasrī. The authenticity of Shankara as the author of the has been questioned and mostly rejected by scholarship.

His authentic works present a harmonizing reading of the shastras, with liberating knowledge of the self at its core, synthesizing the inherited Advaita Vedanta teachings of his time. Also, as per astronomical details given in books Shankara Satpatha, Shankara Vijaya, Brihat Shakara Vijaya and Prachina Shankara Vijaya, it is believed that Shankaracharya was born in 509 BCE. According to Kanhi Peetham, having established his divine mission, the incomparable Sankara attained his BrahmTbhava (identity with Brahman) at Kanchi, in the precincts of Sri Kamakshi, in his 32nd year, in 2625 Kali, in the cyclic year Raktakshi, corresponding to 476 B.C. 507 BCE according to Govardhan Math, 491 BCE according to Dvarka (Dvārakā), 485 BCE according to Jyotirmath, 484 BCE according to Jagannatha Puri, and 483 BCE according to Sringeri.

The records of the Sringeri Matha state that Shankara was born in the 14th year of the reign of "Vikramaditya", but it is unclear to which king this name refers. Though some researchers identify the name with Chandragupta II (4th century CE), modern scholarship accepts the Vikramaditya as being from the Chalukya dynasty of Badami, most likely Vikramaditya II (733–746 CE). According to Frank Whaling, some Hindus, particularly those who follow Advaita, view Shankara as someone who defended Hindu dharma in response to Buddhist and Jain challenges and contributed to the decline of Buddhism in India. His teachings and tradition are central to Smartism and have influenced Sant Mat lineages. Tradition portrays him as the one who reconciled the various sects (Vaishnavism, Shaivism, and Shaktism) with the introduction of the Panchayatna form of worship, the simultaneous worship of five deities – Ganesha, Surya, Vishnu, Shiva, and Devi, arguing that all deities were but different forms of the one Brahman, the invisible Supreme Being, implying that Advaita Vedanta stood above all other traditions.

Historical Shankara and (lack of) early influence (until 10th century)

Scholars have questioned Shankara's early influence in India. The Buddhist scholar Richard E. King states,

According to numerous scholars, Shankara and other early Advaitins were probably Vaishnavites, or at least teaching in a Vaishnava-oriented milieu, and Shankara may have had a Pancharatra background.

According to Clark, "Shankara was relatively unknown during his life-time, and probably for several centuries after, as there is no mention of him in Buddhist or Jain sources for centuries; nor is he mentioned by other important philosophers of the ninth and tenth centuries." According to King, until the 10th century, Shankara's works seem to have been overshadowed by his older contemporary Maṇḍana Miśra; Roodurmun notes that Maṇḍana was considered the major representative of Advaita. Maṇḍana Miśra, a Mimansa scholar, follower of Kumarila Bhatta, and older contemporary of Shankara, wrote the Brahma-siddhi, a seminal text on Advaita that has survived into the modern era. The "theory of error" set forth in the Brahma-siddhi became the normative in later Advaita Vedanta discussion of error. His student Vachaspati Miśra, who is believed by Advaita tradition to have been an incarnation of Shankara to popularize the Advaita view, wrote the Bhamati (Bhāmatī), a commentary on Shankara's Brahma Sutra Bhashya, and the Brahmatattva-samiksa, a commentary on Mandana Mishra's Brahma-siddhi. His thought was mainly inspired by Mandana Mishra, and harmonises Shankara's thought with that of Mandana Mishra. The Bhamati school takes an ontological approach. It sees the jiva (jīva) as the source of avidya (avidyā). believing that Maṇḍana Mishra became a disciple of Shankara after a public debate which Shankara won.

According to Satchidanandendra Sarasvati, "almost all the later Vedantins were influenced" by Mandana Mishra and Bhaskara "in working out their own line of thought". Potter notes that modern interpreters of Advaita such as Satchidanandendra Sarasvati argue that most post-Shankara Advaita Vedanta actually deviates from Shankara, and that only his student Sureśvara - whose interpretation had little influence, represents Shankara correctly. In this view, Shankara's influential student Padmapada misunderstood Shankara, while his views were maintained by the Sureshvara school.

Vaishnavite Vedanta (10th-14th century) Hajime Nakamura states that prior to Shankara, views similar to his already existed, but did not occupy a dominant position within the Vedanta. Until the 11th century, Vedanta itself was a peripheral school of thought; Vedanta became a major influence when it was utilized by various sects of Hinduism to ground their doctrines. The early Vedanta scholars were from the upper classes of society, well-educated in traditional culture. They formed a social elite, "sharply distinguished from the general practitioners and theologians of Hinduism." Their teachings were "transmitted among a small number of selected intellectuals". Works of the early Vedanta schools do not contain references to Vishnu or Shiva. It was only after Shankara that "the theologians of the various sects of Hinduism utilized Vedanta philosophy to a greater or lesser degree to form the basis of their doctrines," whereby "its theoretical influence upon the whole of Indian society became final and definitive." Examples are Ramanuja (11th c.), who aligned bhakti, "the major force in the religions of Hinduism," with philosophical thought, meanwhile rejecting Shankara's views, and the Nath-tradition.

Vijayanagara Empire and Vidyaranya (14th century) - creation of legendary (hagiographic) views

In medieval times, Advaita Vedanta position as most influential Hindu darsana started to take shape, as Advaitins in the Vijayanagara Empire competed for patronage from the royal court, and tried to convert others to their sect. It is only during this period that the historical fame and cultural influence of Shankara and Advaita Vedanta was established. Many of Shankara's biographies were created and published in and after the 14th century, such as Vidyaranya's widely cited Śankara-vijaya. Vidyaranya, also known as Madhava, who was the 12th Jagadguru of the Śringeri Śarada Pītham from 1380 to 1386 and a minister in the Vijayanagara Empire, but his efforts were also targeted at Sri Vaishnava groups, especially Visishtadvaita, which was dominant in territories conquered by the Vijayanagara Empire. Furthermore, sects competed for patronage from the royal court, and tried to convert others to their own sectarian system. Vidyaranya and his brothers, note Paul Hacker and other scholars, wrote extensive Advaitic commentaries on the Vedas and Dharma to make "the authoritative literature of the Aryan religion" more accessible. Vidyaranya was an influential Advaitin, and he created legends to turn Shankara, whose elevated philosophy had no appeal to gain widespread popularity, into a "divine folk-hero who spread his teaching through his digvijaya ("universal conquest," see below) all over India like a victorious conqueror." In his doxography Sarvadarśanasaṅgraha ("Summary of all views") Vidyaranya presented Shankara's teachings as the summit of all darsanas, presenting the other darsanas as partial truths which converged in Shankara's teachings, which was regarded to be the most inclusive system. The Vaishanava traditions of Dvaita and Visishtadvaita were not classified as Vedanta, and placed just above Buddhism and Jainism, reflecting the threat they posed for Vidyaranya's Advaita allegiance. Bhedabheda wasn't mentioned at all, "literally written out of the history of Indian philosophy." Such was the influence of the Sarvadarśanasaṅgraha, that early Indologists also regarded Advaita Vedanta as the most accurate interpretation of the Upanishads. And Vidyaranya founded a matha, proclaiming that it was established by Shankara himself. Vidyaranya enjoyed royal support,

Scholars note that one of the most cited Shankara hagiographies, Anandagiri's, includes stories and legends about historically different people, but all bearing the same name of Sri Shankaracarya or also referred to as Shankara but likely meaning more ancient scholars with names such as Vidya-sankara, Sankara-misra and Sankara-nanda. Some hagiographies are probably written by those who sought to create a historical basis for their rituals or theories.

Early life According to the oldest hagiographies, Shankara was born in the southern Indian state of Kerala, in a village named Kaladi sometimes spelled as Kalati or Karati. According to Anantanandagiri's hagiography, Shankara was born in Chidambaram. According to the narratives, his parents were an aged, childless, couple who led a devout life of service to the poor. They named their child Shankara, meaning "giver of prosperity". His father died while Shankara was very young. Shankara's , the initiation into student-life, had to be delayed due to the death of his father, and was then performed by his mother.

Sannyasa Shankara's hagiographies describe him as someone who was attracted to the life of Sannyasa (hermit) from early childhood. His mother disapproved. A story, found in every hagiography, describes Shankara at age eight going to a river with his mother, Sivataraka, to bathe, where he is caught by a crocodile. Shankara calls out to his mother to give him permission to become a Sannyasin (a religious ascetic), or else the crocodile will kill him. The mother agrees and Shankara is freed, and leaves his home for education. He reaches a Saivite sanctuary along a river in a north-central state of India, and becomes the disciple of a teacher named Govinda Bhagavatpada. The stories in various hagiographies diverge in details about the first meeting between Shankara and his Guru, where they met, as well as what happened later. Several texts suggest Shankara's schooling with Govindapada happened along the river Narmada in Omkareshwar, but a few place it along the River Ganges in Kashi (Varanasi) as well as Badari (Badrinath in the Himalayas).

The hagiographies vary in their description of where he went, whom he met and debated and many other details of his life. Most mention Shankara studying the Vedas, Upanishads and Brahmasutra with Govindapada, and Shankara authoring several key works in his youth, while he was studying with his teacher. It is with his teacher Govinda, that Shankara studied Gaudapadiya Karika, as Govinda was himself taught by Gaudapada. Most also mention a meeting with scholars of the Mimansa school of Hinduism namely Kumarila and Prabhakara, as well as Mandana and various Buddhists, in Shastrartha (an Indian tradition of public philosophical debates attended by large number of people, sometimes with royalty).

Travels (Digvijaya) and disciples

Thereafter, the hagiographies about Shankara vary significantly. Different and widely inconsistent accounts of his life include diverse journeys, pilgrimages, public debates, installation of yantras and lingas, as well as the founding of monastic centers in north, east, west, and south India.

While the details and chronology vary, most hagiographies present Shankara as traveling widely within India, Gujarat to Bengal, and participating in public philosophical debates with different orthodox schools of Hindu philosophy, as well as heterodox traditions such as Buddhists, Jains, Arhatas, Saugatas, and Charvakas. The hagiographies credit him with starting several matha (monasteries), but this is uncertain. Ten monastic orders in different parts of India are generally attributed to Shankara's travel-inspired Sannyasin schools, each with Advaita notions, of which four have continued in his tradition: Bharati (Sringeri), Sarasvati (Kanchi), Tirtha and Asramin (Dvaraka). Other monasteries that record Shankara's visit include Giri, Puri, Vana, Aranya, Parvata and Sagara – all names traceable to the Ashrama system in Hinduism and Vedic literature.

Shankara had a number of disciple scholars during his travels, including Padmapadacharya(also called Sanandana, associated with the text Atma-bodha), Sureśvaracharya, Totakacharya, Hastamalakacharya, Chitsukha, Prthividhara, Chidvilasayati, Bodhendra, Brahmendra, Sadananda and others, who authored their own literature on Shankara and Advaita Vedanta.

Alleged deathplaces According to a number of hagiographies, associated with the four cardinal maths, Adi Shankara died at Kedarnath, a Hindu pilgrimage site in the Himalayas, located in the northern Indian state of Uttarakhand. A 12-foot statue of Shankara was unveiled in 2021 at the reconstructed samadhi sthal (memorial site or tomb) at his alleged deathplace at Kedarnath.

According to the hagiographies related to the Kanchi Kamakoti Peetham Adi Shankara attained siddhi in Kanchi. The nearby Kamakshi Amman Temple of the Shaktism tradition has a shrine dedicated to this supposed final resting place of Adi Shankara. The Vyasacaliya, as well as the Madhaviya, state that Adi Shankara attained siddhi in Kashmir, after meeting Kumarila and Mandana at the Prayaga.

Pande also mentions Kerala as an alleged deathplace. According to the Tibetan Buddhist scholar Taranatha, Shankara ended his life by drowning himself in the Ganges.

Hagiographies: attribution of Mathas and Smarta tradition (14-17th century) Traditionally, Shankara is regarded as the founder of the of Hindu monasticism, and the Panchayatana puja and of the Smarta tradition.

Dashanami Sampradaya and mathas

Advaita Vedanta is, at least in the west, primarily known as a philosophical system. But it is also a tradition of renunciation. Philosophy and renunciation are closely related: Several other Hindu monastic and Ekadandi traditions, however, remained outside the organisation of the Dasanāmis.

According to tradition, Adi Sankara organised the Hindu monks of these ten sects or names under four mathas, with the headquarters at Dvārakā in the West, Jagannatha Puri in the East, Sringeri in the South and Badrikashrama in the North. It consists of the worship of five deities set in a quincunx pattern, the five deities being Shiva, Vishnu, Devi, Surya, and an Ishta Devata such as Kartikeya, or Ganesha or any personal god of devotee's preference. Sometimes the Ishta Devata is the sixth deity in the mandala. Skanda, also known as Kartikeya and Murugan, is added. Panchayatana puja is a practice that became popular in medieval India, However, archaeological evidence suggests that this practice long predates the birth of Adi Shankara. (Many Panchayatana mandalas and temples have been uncovered that are from the Gupta Empire period, and one Panchayatana set from the village of Nand (about 24 kilometers from Ajmer) has been dated to belong to the Kushan Empire era (pre-300 CE).) The Kushan period set includes Shiva, Vishnu, Surya, Brahma and one deity whose identity is unclear.

Authentic works

Shankara is most known for his systematic reviews and commentaries (bhashyas) on ancient Indian texts. Shankara's masterpiece of commentary is the Brahmasutrabhashya (literally, commentary on Brahma Sutras). The Brahma Sutras are a fundamental text of the Vedanta school of Hinduism. Shankara refers to or cites some passages from works attributed to Gaudapada (the teacher of Shankara's teacher) in his commentaries, revealing a line of influence.

According to Flood, of the Upanishadic commentaries only his commentaries on the Brihadaranyaka Upanishad and the Taittiriya Upanishad are authentic. Hacker and Mayeda also accept as authentic the commentaries on the Chandogya Upanishad, the Aitareya Upanishad, the Kena Upanishad, the Isha Upanishad, the Katha Upanishad, and the Prashna Upanishad. The authenticity of the commentary on the Mandukya Upanishad and Gaudapadas Madukya-karika has been questioned.

Other authentic works of Shankara include commentaries on the Bhagavad Gita (part of his Prasthana Trayi Bhasya). His Vivarana (tertiary notes) on the commentary by Vedavyasa on Yogasutras as well as those on Apastamba Dharma-sũtras (Adhyatama-patala-bhasya) are accepted by scholars as authentic works of Shankara. Among the Stotra (poetic works), the Dakshinamurti Stotra, the Mohamudgara Stotra(Bhaja govindam), the Shivanandalahari, the Carpata-panjarika, the Visnu-satpadi, the Harimide, the Dasha-shloki, and the Krishna-staka are likely to be authentic.

Shankara also authored Upadesasahasri, his most important original philosophical work. Of other original Prakaranas (प्रकरण, monographs, treatise), seventy-six works are attributed to Shankara. Modern era Indian scholars such as Belvalkar as well as Upadhyaya accept five and thirty-nine works respectively as authentic.

Shankara's stotras considered authentic include those dedicated to Krishna (Vaishnavism) and one to Shiva (Shaivism) – often considered two different sects within Hinduism. Scholars suggest that these stotra are not sectarian, but essentially Advaitic and reach for a unified universal view of Vedanta.

Shankara's commentary on the Brahma Sutras is the oldest surviving. However, in that commentary, he mentions older commentaries like those of Dravida, Bhartrprapancha and others which are either lost or yet to be found.

Works of doubtful authenticity or not authentic Commentaries on Nrisimha-Purvatatapaniya and Shveshvatara Upanishads are attributed to Shankara, but their authenticity is highly doubtful. Similarly, commentaries on several early and later Upanishads attributed to Shankara are rejected by scholars has been rejected by modern scholarship. According to Grimes, "modern scholars tend to reject its authenticity as a work by Shankara," while "traditionalists tend to accept it."

The Aparokshanubhuti and Atma bodha are also attributed to Shankara, as his original philosophical treatises, but modern scholarship does not regard them to be composed by Shankara.

Paul Hacker has also expressed some reservations that the compendium Sarva-darsana-siddhanta Sangraha was completely authored by Shankara, because of difference in style and thematic inconsistencies in parts. Similarly, Gayatri-bhasya is doubtful to be Shankara's work. Other commentaries that are highly unlikely to be Shankara's work include those on Uttaragita, Siva-gita, Brahma-gita, Lalita-shasranama, Suta-samhita and Sandhya-bhasya. The commentary on the Tantric work Lalita-trisati-bhasya attributed to Shankara is also unauthentic.

Shankara is widely credited with commentaries on other scriptural works, such as the Vishnu sahasranāma and the Sānatsujātiya, but both these are considered apocryphal by scholars who have expressed doubts. Hastamalakiya-bhasya is also widely believed in India to be Shankara's work and it is included in Samata-edition of Shankara's works, but some scholars consider it to be the work of Shankara's student.

Philosophy and practice

According to Koller, Shankara, and his contemporaries, made a significant contribution in understanding Buddhism and the ancient Vedic traditions, then transforming the extant ideas, particularly reforming the Vedanta tradition of Hinduism, making it India's most important "spiritual tradition" for more than a thousand years. Benedict Ashley credits Adi Shankara for unifying two seemingly disparate philosophical doctrines in Hinduism, namely Atman and Brahman.

According to Nakamura, Shankara was not an original thinker, but systematised the works of preceding philosophers. The central theme of Shankara's writings is the liberating knowledge of the true identity of the Self (jivĀtman) as Brahman. Moksha is attained in this life by recognizing this true identity, which is revealed by the Mahavakyas, especially Tat Tvam Asi, "That you are."

Historical context

Shankara lived in the time of the great "Late classical Hinduism", which lasted from 650 till 1100 CE. This era was one of political instability that followed the Gupta dynasty and King Harsha of the 7th century CE. Power became decentralised in India. Several larger kingdoms emerged, with "countless vassal states". The kingdoms were ruled via a feudal system. Smaller kingdoms were dependent on the protection of the larger kingdoms. "The great king was remote, was exalted and deified", as reflected in the Tantric Mandala, which could also depict the king as the centre of the mandala.

The disintegration of central power also led to regionalisation of religiosity and religious rivalry. Local cults and languages were enhanced, and the influence of "Brahmanic ritualistic Hinduism" was diminished. Rural and devotional movements arose, along with Shaivism, Vaisnavism, Bhakti and Tantra, though "sectarian groupings were only at the beginning of their development". Religious movements had to compete for recognition by the local lords, and Buddhism, Jainism, Islam and various traditions within Hinduism were competing for members. Buddhism in particular had emerged as a powerful influence in India's spiritual traditions in the first 700 years of the 1st millennium CE, but lost its position after the 8th century, and began to disappear in India. This was reflected in the change of puja-ceremonies at the courts in the 8th century, where Hindu gods replaced the Buddha as the "supreme, imperial deity".

Systematizer of Advaita According to Nakamura, comparison of the known teachings of the early Vedantins and Shankara's thought shows that most of the characteristics of Shankara's thought "were advocated by someone before Śankara". Shankara "was the person who synthesized the Advaita-vāda which had previously existed before him". According to Nakamura, after the growing influence of Buddhism on Vedānta, culminating in the works of Gauḍapāda, Adi Shankara gave a Vedantic character to the Buddhistic elements in these works, synthesising and rejuvenating the doctrine of Advaita.

According to Koller, using ideas in ancient Indian texts, Shankara systematized the foundation for Advaita Vedānta in the 8th century, reforming Badarayana's Vedānta tradition. According to Mayeda, Shankara represents a turning point in the development of Vedānta, yet he also notices that it is only since Deussens's praise that Shankara "has usually been regarded as the greatest philosopher of India." Mayeda further notes that Shankara was primarily concerned with moksha, "and not with the establishment of a complete system of philosophy or theology," following Potter, who qualifies Shankara as a "speculative philosopher." Lipner notes that Shankara's "main literary approach was commentarial and hence perforce disjointed rather than procedurally systematic [...] though a systematic philosophy can be derived from Samkara's thought."

Shankara has been described as influenced by Shaivism and Shaktism, but his works and philosophy suggest greater overlap with Vaishnavism, influence of Yoga school of Hinduism, but most distinctly express his Advaitin convictions with a monistic view of spirituality, and his commentaries mark a turn from realism to idealism.

Moksha - liberating knowledge of Brahman The central theme of Shankara's writings is the liberating knowledge of the true identity of jivatman (individual self) as Ātman-Brahman. One of Shankara's main concerns was establishing the Upanishads as an independent means of knowledge beyond the ritually oriented Mimansa exegesis of the vedas.

According to Shankara, the one unchanging entity (Brahman) alone is real, while changing entities do not have absolute existence. Shankara's primary objective was to explain how moksha is attained in this life by recognizing the true identity of jivatman as Atman-Brahman, as mediated by the Mahāvākyas, especially Tat Tvam Asi, "That you are." Correct knowledge of jivatman and Atman-Brahman is the attainment of Brahman, immortality, and leads to moksha (liberation) from suffering and samsara, the cycle of rebirth. This is stated by Shankara as follows: According to Joshua Anderson, liberation in Advaita Vedanta should be seen as 'psychological' rather than 'metaphysical'. That is to say, moksha is a 'shift in perspective' rather than 'an ontological change in being'. It alters how one experiences the phenomenal world rather than what one fundamentally is. NB: some manuscripts list Upadesasahasri verse 1.18.133 as 2.18.133, while Mayeda lists it as 1.18.133, because of interchanged chapter numbering. See Upadesa Sahasri: A Thousand Teachings, S Jagadananda (Translator, 1949), , Verse 2.8.133, p. 258; Karl H Potter (2014), The Encyclopedia of Indian Philosophies, Volume 3, Princeton University Press, , p. 249 but his thematic focus was upon metaphysics and soteriology, and he took for granted the pramanas, that is epistemology or "means to gain knowledge, reasoning methods that empower one to gain reliable knowledge". According to Sengaku Mayeda, "in no place in his works [...] does he give any systematic account of them," taking Atman-Brahman to be self-evident (svapramanaka) and self-established (svatahsiddha), and "an investigation of the means of knowledge is of no use for the attainment of final release." Mayeda notes that Shankara's arguments are "strikingly realistic and not idealistic," arguing that jnana is based on existing things (vastutantra), and "not upon Vedic injunction (codanatantra) nor upon man (purusatantra).

According to Michael Comans (aka Vasudevacharya), Shankara considered perception and inference as a primary most reliable epistemic means, and where these means to knowledge help one gain "what is beneficial and to avoid what is harmful", there is no need for or wisdom in referring to the scriptures. In certain matters related to metaphysics and ethics, says Shankara, the testimony and wisdom in scriptures such as the Vedas and the Upanishads become important.

Merrell-Wolff states that Shankara accepts Vedas and Upanishads as a source of knowledge as he develops his philosophical theses, yet he never rests his case on the ancient texts, rather proves each thesis, point by point using the pramanas (means of knowledge) of reason and experience. Hacker and Phillips note that his insight into rules of reasoning and hierarchical emphasis on epistemic steps is "doubtlessly the suggestion" of Shankara in Brahma-sutra-bhasya, an insight that flowers in the works of his companion and disciple Padmapada.

Logic versus revelation Stcherbatsky in 1927 criticized Shankara for demanding the use of logic from Madhyamika Buddhists, while himself resorting to revelation as a source of knowledge. Sircar in 1933 offered a different perspective and stated, "Sankara recognizes the value of the law of contrariety and self-alienation from the standpoint of idealistic logic; and it has consequently been possible for him to integrate appearance with reality."

Recent scholarship states that Shankara's arguments on revelation are about apta vacana (Sanskrit: आप्तवचन, sayings of the wise, relying on word, testimony of past or present reliable experts). It is part of his and Advaita Vedanta's epistemological foundation. The Advaita Vedanta tradition considers such testimony epistemically valid, asserting that a human being needs to know numerous facts, and with the limited time and energy available, he can learn only a fraction of those facts and truths directly. Shankara considered the teachings in the Vedas and Upanishads as apta vacana and a valid source of knowledge. To Shankara, that knowledge of Brahman springs only from inquiry into the teachings of the Upanishads. The method of yoga, encouraged in Shankara's teachings notes Comans, includes withdrawal of mind from sense objects as in Patanjali's system, but it is not complete thought suppression, instead it is a "meditative exercise of withdrawal from the particular and identification with the universal, leading to contemplation of oneself as the most universal, namely, Consciousness". Describing Shankara's style of yogic practice, Comans writes: the type of yoga which Sankara presents here is a method of merging, as it were, the particular (visesa) into the general (samanya). For example, diverse sounds are merged in the sense of hearing, which has greater generality insofar as the sense of hearing is the locus of all sounds. The sense of hearing is merged into the mind, whose nature consists of thinking about things, and the mind is in turn merged into the intellect, which Sankara then says is made into 'mere cognition' (vijnanamatra); that is, all particular cognitions resolve into their universal, which is cognition as such, thought without any particular object. And that in turn is merged into its universal, mere Consciousness (prajnafnaghana), upon which everything previously referred to ultimately depends. While this methodology has roots in the theoretical works of Nyaya school of Hinduism, Shankara consolidated and applied it with his unique exegetical method called Anvaya-Vyatireka, which states that for proper understanding one must "accept only meanings that are compatible with all characteristics" and "exclude meanings that are incompatible with any".

The Mahāvākyas - true identity as Ātman-Brahman Moksha, liberation from suffering and rebirth and attaining immortality, is attained by disidentification from the body-mind complex and gaining self-knowledge as being in essence Atman-Brahman. According to Shankara, the individual jivĀtman and Brahman seem different at the empirical level of reality, but this difference is only an illusion, and at the highest level of reality they are really identical. The real self is Sat, "the Existent," that is, Ātman-Brahman. Whereas the difference between Ātman and non-Ātman is deemed self-evident, knowledge of the true identity of jivĀtman as Brahman is revealed by the shruti, especially the Upanishadic statement tat tvam asi.

Mahāvākyas According to Shankara, a large number of Upanishadic statements reveal the true identity of jivĀtman as Brahman. In the Advaita Vedānta tradition, four of those statements, the Mahāvākyas, which are taken literal, in contrast to other statements, have a special importance in revealing this identity. They are: तत्त्वमसि, tat tvam asi, Chandogya VI.8.7. Traditionally rendered as "That Thou Art" (that you are), with tat in Ch.U.6.8.7 referring to sat, "the Existent"); correctly translated as "That's how [thus] you are," with tat in Ch.U.6.12.3, it' original location from where it was copied to other verses, referring to "the very nature of all existence as permeated by [the finest essence]" अहं ब्रह्मास्मि, aham brahmāsmi, Brhadāranyaka I.4.10, "I am Brahman," or "I am Divine." प्रज्ञानं ब्रह्म, prajñānam brahma, Aitareya V.3, "Prajñānam is Brahman." ("the Absolute", or Brahman, the Real, the "Root of the world," the true essence or root or origin of everything that exists.) Shankara adds in another verse of the Upadesasahasri that the inner Self is "free from caste, family, and purifying ceremonies." As Shankara states in the Upadesasahasri:

The statement "tat tvam asi" sheds the false notion that Atman is different from Brahman. According to Nakamura, the non-duality of atman and Brahman "is a famous characteristic of Sankara's thought, but it was already taught by Sundarapandya" ( or earlier). Shankara cites Sundarapandya in his comments to Brahma Sutra verse I.1.4:

From this, and a large number of other accordances, Nakamura concludes that Shankar was not an original thinker, but "a synthesizer of existing Advaita and the rejuvenator, as well as a defender, of ancient learning."

Meditation on the Mahāvākya In the Upadesasahasri Shankara, Shankara is ambivalent on the need for meditation on the Upanishadic mahavyaka. He states that "right knowledge arises at the moment of hearing," and rejects prasamcaksa or prasamkhyana meditation, that is, meditation on the meaning of the sentences, and in Up.II.3 recommends parisamkhyana, separating Atman from everything that is not Atman, that is, the sense-objects and sense-organs, and the pleasant and unpleasant things and merit and demerit connected with them. Yet, Shankara then concludes with declaring that only Atman exists, stating that "all the sentences of the Upanishads concerning non-duality of Atman should be fully contemplated, should be contemplated." As Mayeda states, "how they [prasamcaksa or prasamkhyana versus parisamkhyana] differ from each other is not known."

Prasamkhyana was advocated by Mandana Misra, the older contemporary of Shankara. "According to Mandana, the mahavakyas are incapable, by themselves, of bringing about brahmajnana. The Vedanta-vakyas convey an indirect knowledge which is made direct only by deep meditation (prasamkhyana). The latter is a continuous contemplation of the purport of the mahavakyas. Vācaspati Miśra, a student of Mandana Misra, agreed with Mandana Misra, and their stance is defended by the Bhamati-school, founded by Vācaspati Miśra. In contrast, the Vivarana school founded by Prakasatman (–1300) follows Shankara closely, arguing that the mahavakyas are the direct cause of gaining knowledge.

Renouncement of ritualism Shankara, in his text Upadesasahasri, discourages ritual worship such as oblations to Deva (God), because that assumes the Self within is different from the Brahman. The "doctrine of difference" is wrong, asserts Shankara, because, "he who knows the Brahman is one and he is another, does not know Brahman". The false notion that Atman is different from Brahman is connected with the novice's conviction that (Upadeshasahasri II.1.25)

Recognizing oneself as "the Existent-Brahman," which is mediated by scriptural teachings, is contrasted with the notion of "I act," which is mediated by relying on sense-perception and the like. According to Shankara, the statement "Thou art That" "remove the delusion of a hearer," "so through sentences as "Thou art That" one knows one's own Atman, the witness of all internal organs," and not from any actions. With this realization, the performance of rituals is prohibited, "since [the use of] rituals and their requisites is contradictory to the realization of the identity [of Atman] with the highest Atman."

However, Shankara also asserts that Self-knowledge is realized when one's mind is purified by an ethical life that observes Yamas such as Ahimsa (non-injury, non-violence to others in body, mind and thoughts) and Niyamas. Rituals and rites such as yajna (a fire ritual), asserts Shankara, can help draw and prepare the mind for the journey to Self-knowledge. He emphasizes the need for ethics such as Akrodha and Yamas during Brahmacharya, stating the lack of ethics as causes that prevent students from attaining knowledge.

Īśvara Shankara, while rejecting empirical reality due to his position of nonduality, still attributes value to the universe as it identifies with Īśvara. He sometimes blurs the distinction between Īśvara and Brahman, using various terms for both. However, he generally separates Īśvara, associated with the universe and its attributes, from the absolute nondual Brahman. In his commentary on the Brahmasutra, Shankara uses the term Īśvara or Parameśvara (highest Īśvara) to refer to absolute Brahman. Drawing from the Upanishads, Shankara sees Īśvara as the universe's material and intelligent cause, emanating it through the power of maya, thereby making the universe sentient and self-aware. In relation to the Mandukya Upanishad, Shankara compares the universe's unmanifest state to Īśvara in a deep dreamless cosmic state.

Shankara's conception of Brahman as the cause of the world does not invoke creation in the literal sense but vivartta (manifoldness without transformation), distinct from satkaryavada (actual transformation). Shankara argues that insentient matter cannot act purposefully and rejects any actual transformation of Brahman.

Influences of Mahayana Buddhism

Shankara's Vedanta shows similarities with Mahayana Buddhism; opponents have even accused Shankara of being a "crypto-Buddhist," a qualification which is rejected by the Advaita Vedanta tradition, given the differences between these two schools. According to Shankara, a major difference between Advaita and Mahayana Buddhism are their views on Atman and Brahman. According to both Loy and Jayatilleke, more differences can be discerned. Suthren Hirst and others have also noted that Shankara's advaita may stem from a Vaishnavite advaita tradition.

Similarities and influences Despite Shankara's criticism of certain schools of Mahayana Buddhism, Shankara's philosophy shows strong similarities with the Mahayana Buddhist philosophy which he attacks. According to S.N. Dasgupta,

According to Mudgal, Shankara's Advaita and the Buddhist Madhyamaka view of ultimate reality are compatible because they are both transcendental, indescribable, non-dual and only arrived at through a via negativa (neti neti). Mudgal concludes therefore that

Some Hindu scholars criticized Advaita for its Maya and non-theistic doctrinal similarities with Buddhism. Ramanuja, the founder of Vishishtadvaita Vedānta, accused Adi Shankara of being a Prachanna Bauddha, that is, a "crypto-Buddhist", and someone who was undermining theistic Bhakti devotionalism. The non-Advaita scholar Bhaskara of the Bhedabheda Vedānta tradition, similarly around 800 CE, accused Shankara's Advaita as "this despicable broken down Mayavada that has been chanted by the Mahayana Buddhists", and a school that is undermining the ritual duties set in Vedic orthodoxy.

Differences The qualification of "crypto-Buddhist" is rejected by the Advaita Vedanta tradition, highlighting their respective views on Atman, Anatta and Brahman. There are differences in the conceptual means of "liberation." Nirvana, a term more often used in Buddhism, is the liberating 'blowing out' of craving, aided by the realization and acceptance that there is no Self (anatman) as the center of perception, craving, and delusion. Moksha, a term more common in Hinduism, is the similar liberating release from craving and ignorance, yet aided by the realization and acceptance that one's inner Self is not a personal 'ego-self', but a Universal Self.

Films Shankaracharya (1927), Indian silent film about Shankara by Kali Prasad Ghosh. Jagadguru Shrimad Shankaracharya (1928), Indian silent film by Parshwanath Yeshwant Altekar. On 15 August 2013, Jagadguru Adi Shankara was released in an Indian Telugu-language biographical film written and directed by J. K. Bharavi and was later dubbed in Kannada with the same title, by Upendra giving narration for the Kannada dubbed version