and the Ātman The central concern of all Upanishads is to discover the relations between ritual, cosmic realities (including gods), 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. The Upanishads reflect a pluralism of worldviews. While some Upanishads have been deemed 'monistic', others, including the
Katha Upanishad, are
dualistic. 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. They contain a plurality of ideas. 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 declarations of
Ahimsa (non-violence) as an ethical precept. 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. Similarly, the Karma doctrine is presented in the
Brihadaranyaka Upanishad, which is the oldest Upanishad.
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. 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 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''. 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". The
Mundaka Upanishad declares how man has been called upon, promised benefits for, scared unto and misled into performing sacrifices, oblations and pious works. The
Maitri Upanishad states, {{Blockquote|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, meditate on the Self, to become complete and perfect. But who is to be meditated on? 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. 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. 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. Brahman-Atman and self-realization develops, in the Upanishad, as the means to
moksha (liberation; freedom in this life or after-life). According to
Jayatilleke, the thinkers of Upanishadic texts can be grouped into two categories. One group, which includes early Upanishads along with some middle and late Upanishads, were composed by metaphysicians who used rational arguments and empirical experience to formulate their speculations and philosophical premises. The second group includes many middle and later Upanishads, where their authors professed theories based on yoga and personal experiences. Yoga philosophy and practice, adds Jayatilleke, is "not entirely absent in the Early Upanishads". The development of thought in these Upanishadic theories contrasted with Buddhism, since the Upanishadic inquiry fails to find an empirical correlate of the assumed Atman, but nevertheless assumes its existence, "[reifying] consciousness as an eternal self." The Buddhist inquiry "is satisfied with the empirical investigation which shows that no such Atman exists because there is no evidence," states Jayatilleke.
Atman and Brahman The Upanishads postulate
Ātman and
Brahman as the "summit of the hierarchically arranged and interconnected universe." Both have multiple meanings, and various ideas about the relation between Atman and Brahman can be found. Atman has "a wide range of lexical meanings, including ‘breath’, ‘spirit’, and ‘body’." In the Upanishads it refers to the body, but also to the essence of the concrete physical human body, "an essence, a life-force, consciousness, or ultimate reality." The Chāndogya Upaniṣad (6.1-16) "offers an organic understanding of ātman, characterizing the self in terms of the life force that animates all living beings," while the Bṛhadāraṇyaka Upaniṣad "characterizes ātman more in terms of consciousness than as a life-giving essence." Brahman may refer to a "formulation of truth," but also to "the ultimate and basic essence of the cosmos," standing at the "summit of the hierarchical scheme, or at the bottom as the ultimate foundation of all things." Brahman is "beyond the reach of human perception and thought." Atman likewise has multiple meanings, one of them being 'self', the inner essence of a human body/person. Various ideas about the relation between Atman and Brahman can be found. Two distinct, somewhat divergent themes stand out. Older upanishads state that
Atman is part of Brahman but not identical, while younger Upanishads state that Brahman (Highest Reality, Universal Principle, Being-Consciousness-Bliss) is identical with
Atman. The
Brahmasutra by Badarayana ( 100 BCE) synthesized and unified these somewhat conflicting theories. According to Nakamura, the Brahmasutras see Atman and Brahman as both different and not-different, a point of view which came to be called
bhedabheda in later times. According to Koller, the Brahmasutras state 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. This ancient debate flowered into various dual, non-dual theories in Hinduism.
Reality and Maya Two different types of the non-dual Brahman-Atman are presented in the Upanishads, according to Mahadevan. The one in which the non-dual Brahman-Atman is the all-inclusive ground of the universe and another in which empirical, changing reality is an appearance (Maya). 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). 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). 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." 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." In the Upanishads, Māyā is the perceived changing reality and it co-exists with Brahman which is the hidden true reality.
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. ==Schools of Vedanta==