Nondualism in the context of "Nirvana (Buddhism)"

Hindu philosophy or Vedic philosophy is the set of philosophical systems that developed in tandem with the first Hindu religious traditions during the iron and classical ages of India. In Indian philosophy, of which Hindu philosophy is a prominent subset, the word used for philosophy is Darshana (Sanskrit: दर्शन; meaning: "viewpoint or perspective"), from the Sanskrit root 'दृश' (drish) meaning 'to see, to experience'.

The schools of thought or Darshanas within Hindu philosophy largely equate to the six ancient orthodox schools: the āstika (Sanskrit: आस्तिक) schools, defined by their acceptance of the Vedas, the oldest collection of Sanskrit texts, as an authoritative source of knowledge. Of these six, Samkhya (सांख्य) is the earliest school of dualism; Yoga (योग) combines the metaphysics of Samkhya with meditation and breath techniques; Nyaya (न्याय) is a school of logic emphasising direct realism; Vaisheshika (वैषेशिक) is an offshoot of Nyaya concerned with atomism and naturalism; Mimamsa (मीमांसा) is a school justifying ritual, faith, and religious obligations; and Vedanta (वेदान्त) contains various traditions that mostly embrace nondualism.

Mysticism encompasses religious traditions of human transformation aided by various practices and religious experiences. Popularly, mysticism is used synonymously with mystical experience, a neologism which refers to an ecstatic unitive experience of becoming one with God, the Absolute, or all that exists.

Scholarly research since the 1970s had questioned this understanding, noting that what appears to be mysticism may also refer to the attainment of insight into ultimate or hidden truths, as in Buddhist awakening and Hindu prajna, in nondualism, and in the realisation of emptiness and ego-lessness, and also to altered states of consciousness such as samadhi.

In Hinduism, the conception of God varies in its diverse religio-philosophical traditions. Hinduism comprises a wide range of beliefs about God and divinity, such as henotheism, monotheism, polytheism, panentheism, pantheism, pandeism, monism, agnosticism, atheism, and nontheism.

Forms of theism find mention in the Bhagavad Gita. Emotional or loving devotion (bhakti) to a primary god such as avatars of Vishnu (Krishna for example), Shiva, and Devi (as emerged in the early medieval period) is now known as the Bhakti movement. Contemporary Hinduism can be categorized into four major theistic Hindu traditions: Vaishnavism, Shaivism, Shaktism, and Smartism. Vaishnavism, Shaivism, and Shaktism worship the Hindu deities Vishnu, Shiva, and Devi as the Supreme God respectively, or consider all Hindu deities as aspects of the same, Supreme Reality or the eternal and formless metaphysical Absolute, called Brahman in Hinduism, or, translated from Sanskrit terminology, Svayaṁ-Bhāgavan ("God Itself"). Other minor sects such as Ganapatya and Saura focus on the deities Ganesha or Surya as the Supreme.

Vajrayāna (Sanskrit: वज्रयान, lit. 'Diamond Vehicle or Thunderbolt Vehicle'), otherwise known as Mantrayāna ("Mantra Vehicle"), Guhyamantrayāna ("Secret Mantra Vehicle"), Tantrayāna ("Tantra Vehicle"), Indo-Tibetan Buddhism, Tantric Buddhism, and Esoteric Buddhism, is a Mahāyāna Buddhist tradition that emphasizes esoteric practices and rituals aimed at rapid spiritual awakening. Emerging between the 5th and 7th centuries CE in medieval India, Vajrayāna Buddhism incorporates a range of techniques, including the use of mantras (sacred sounds), dhāraṇīs (mnemonic codes), mudrās (symbolic hand gestures), mandalās (spiritual diagrams), and the visualization of deities and Buddhas. These practices are designed to transform ordinary experiences into spiritual paths toward enlightenment and liberation, often by engaging with aspects of desire and aversion in a ritualized context.

A distinctive feature of Vajrayāna Buddhism is its emphasis on esoteric transmission, where teachings are passed directly from teacher (guru or vajrācārya) to student through initiation ceremonies. Tradition asserts that these teachings have been passed down through an unbroken lineage going back to the historical Buddha (c. the 5th century BCE), sometimes via other Buddhas or bodhisattvas (e.g., Vajrapani). This lineage-based transmission ensures the preservation of the purity and effectiveness of the teachings. Practitioners often engage in deity yoga, a meditative practice where one visualizes oneself as a deity embodying enlightened qualities to transform one's perception of reality. The tradition also acknowledges the role of feminine energy, venerating female Buddhas and ḍākiṇīs (spiritual beings), and sometimes incorporates practices that challenge conventional norms to transcend dualistic thinking.

Dualism in Indian philosophy is a belief, or large spectrum of beliefs, held by certain schools of Indian philosophy that reality is fundamentally composed of two parts or two types of existence. This mainly takes the form of either mind-matter dualism, as in some strands of Buddhist philosophy, or consciousness-nonconsciousness dualism in the Samkhya and Yoga schools of Hindu philosophy. These can be compared and contrasted with mind-body dualism in Western philosophy of mind and metaphysics.

Another form of dualism in Hindu philosophy is found in the Dvaita ("dualism") Vedanta school, which regards God and the world as two realities with distinct essences; this is a form of theistic dualism. By contrast, schools such as Advaita ("nondualism") Vedanta embrace nondualism or absolute monism, regarding dualism as an illusion (maya).

The Mahāvākyas (sing.: mahāvākyam, महावाक्यम्; plural: mahāvākyāni, महावाक्यानि) are "The Great Sayings" of the Upanishads, with mahā meaning great and vākya, a sentence. The Mahāvākyas are traditionally considered to be four in number, though actually five are prominent in the post-Vedic literature:

1. Tat Tvam Asi (तत् त्वम् असि) – literally translated as "That Thou Art" ("That is you" or "You are that"), appears in Chandogya Upanishad 6.8.7 of the Sama Veda, with tat in Ch.U. 6.8.7 referring to *sat, "the Existent," and contextually understood as "That's how [thus] you are," with tat in Ch.U. 6.12.3 referring to "the very nature of all existence as permeated by [the finest essence]."
2. Ahaṁ Brahmāsmi (अहं ब्रह्मास्मि) - "I am Brahman", or "I am absolute" (Brihadaranyaka Upanishad 1.4.10 of the Yajur Veda)
3. Prajñānaṁ Brahma (प्रज्ञानं ब्रह्म) - "Prajñāna is Brahman", or "Brahman is Prajñāna" (Aitareya Upanishad 3.3 of the Rig Veda)
4. Ayam Ātmā Brahma (अयम् आत्मा ब्रह्म) - "This Self (Atman) is Brahman" (Mandukya Upanishad 1.2 of the Atharva Veda)
5. Sarvaṃ Khalvidaṃ Brahma - "All this indeed is Brahman"(Chāndogya Upaniṣad 3.14.1)

Mahāvākyas are instrumental in Advaita Vedanta, as they are regarded as valid scriptural statements that reveal the self (ātmán), which appears as a separate individual existence (jīva), is, in essence, non-different (not two-ness) from Brahman, which, according to Advaita, is nirguna. In contrast, these statements are less prominent in most other Hindu traditions, which emphasize a qualified or dualistic relationship between the self and Brahman, whom they regard as saguna, often identified with Vishnu, Shiva, Shakti, etc.