the six Vedic schools of thought:
The six Astika or orthodox (accepting the authority of the Vedas) schools of Hindu philosophy are Nyaya, Vaisheshika, Samkhya, Yoga, Purva Mimamsa (also called just 'Mimamsa'), and Uttara Mimamsa (also called 'Vedanta'). The non-Vedic schools are called Nastika, or heterodox, and refer to Buddhism, Jainism and Lokayata. The schools that continue to affect Hinduism today are Purva Mimamsa, Yoga, and Vedanta. See Hindu philosophy for a discussion of the historical significance of Samkhya, Nyaya, and Vaisheshika.
The main objective of the Purva ("earlier") Mimamsa school was to establish the authority of the Vedas. Consequently this school's most valuable contribution to Hinduism was its formulation of the rules of Vedic interpretation. Its adherents believed that revelation must be proved by reasoning, that it should not be accepted blindly as dogma. This empirical and eminently sensible manner of religious application is key to the Sanatana/Hindu Dharma and was especially championed by rationalists like Adi Sankara and Swami Vivekananda. For greater depth, please see Purva Mimamsa
The Yoga system is generally considered to have arisen from the Samkhya philosophy. The yoga referred to here, however, is specifically Raja Yoga (or meditational union). It is based on the sage Patanjali's extremely influential text entitled the Yoga Sutra, which is essentially a compilation and systematization of meditational Yoga philosophy that came before. Upanishads and Bhagavad Gita are also indispensable literature in the study of Yoga.
The most significant difference from Samkhya is that the Yoga school not only incorporates the concept of Ishvara (a personal God) into its metaphysical worldview but also that it holds Ishvara as the ideal upon which to meditate. This is because Ishvara is the only aspect of purusha (the infinite Divine Ground) that has not become entangled with prakrti (the temporal creative forces). It also utilizes the Brahman/Atman terminology and concepts that are found in depth in the Upanishads, adopting Vedantic monist concepts. Realization of the goal of Yoga is known as moksha or samadhi. It, like the Upanishads, seeks realization of the Atman as being nothing other than the infinite Brahman through ethical (mind), physical (body) and meditational (soul) practices of one-pointedness on the 'one supreme truth.' See Yoga for an in-depth look at its history.
Uttara Mimamsa: The Three Schools of Vedanta
The Uttara ("later") Mimamsa school is perhaps one of the cornerstone movements of Hinduism and certainly was responsible for a new wave of philosophical and meditative inquiry, renewal of faith, and cultural reform. Primarily associated with the Upanishads and their commentary by Badarayana, the Vedanta Sutras, Vedanta thought split into three groups, initiated by the thinking and writing of Adi Sankara. Most Hindu thought today in some way relates to changes affected by Vedantic thought, which focused on meditation, morality and centeredness on the one Self rather than on rituals and meaningless societal distinctions like caste.
Pure Monism: Advaita Vedanta
Advaita literally means "not two"; thus this is what we refer to as a monistic (or non-dualistic) system, which emphasises oneness. Its consolidator was Shankara (788-820). Shankara expounded his theories largely based on previous teachings of the Upanishads and his own guru Gaudapada. By analysis of experiential consciousness, he exposed the relative nature of the world and established the non-dual reality of Brahman in which Atman (the individual soul) and Brahman (the ultimate reality) are identified absolutely. It is not merely philosophy, but a conscious system of applied ethics and meditation, all geared towards attaining peace and understanding of truth. Adi Shankara denounced caste and meaningless ritual as foolish, and in his own charismatic manner, exhorted the true devotee to meditate on God's love and apprehend truth. See Advaita for more.
Qualified Monism: Vishistadvaita Vedanta
Ramanuja (1040 - 1137) was the foremost proponent of the concept of Sriman Narayana as the supreme Brahman. He taught that Ultimate reality had three aspects: Ishvara (Vishnu), cit (soul) and acit (matter). Vishnu is the only independent reality, while souls and matter are dependent on God for their existence. Because of this qualification of Ultimate reality, Ramanuja's system is known as qualified non-dualism.
Dualism: Dvaita Vedanta
Like Ramanuja, Madhva (1199 - 1278) identified god with Vishnu, but his view of reality was purely dualistic in that he understood a fundamental differentiation between the ultimate godhead and the individual soul, and the system is therefore called Dvaita (dualistic) Vedanta.
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