In Indian philosophy, Yoga is the name of one of the six orthodox philosophical schools. The Yoga philosophical system is closely allied with the Samkhya school. The Yoga school as expounded by the sage Patanjali accepts the Samkhya psychology and metaphysics, but is more theistic than the Samkhya, as evidenced by the addition of a divine entity to the Samkhya's twenty-five elements of reality. The parallels between Yoga and Samkhya were so close that Max Müller says that "the two philosophies were in popular parlance distinguished from each other as Samkhya with and Samkhya without a Lord...." The intimate relationship between Samkhya and Yoga is explained by Heinrich Zimmer:

These two are regarded in India as twins, the two aspects of a single discipline. Sankhya provides a basic theoretical exposition of human nature, enumerating and defining its elements, analyzing their manner of co-operation in a state of bondage (bandha), and describing their state of disentanglement or separation in release (moksa), while Yoga treats specifically of the dynamics of the process for the disentanglement, and outlines practical techniques for the gaining of release, or 'isolation-integration' (kaivalya).

Patanjali is widely regarded as the founder of the formal Yoga philosophy. Patanjali's yoga is known as Raja yoga, which is a system for control of the mind. Patanjali defines the word "yoga" in his second sutra, which is the definitional sutra for his entire work:

(yogas citta-vrtti-nirodhah)

- Yoga Sutras

This terse definition hinges on the meaning of three Sanskrit terms. I. K. Taimni translates it as "Yoga is the inhibition (nirodhah) of the modifications (vrtti) of the mind (citta)". The use of the word nirodhah in the opening definition of yoga is an example of the important role that Buddhist technical terminology and concepts play in the Yoga Sutra; this role suggests that Patanjali was aware of Buddhist ideas and wove them into his system. Swami Vivekananda translates the sutra as "Yoga is restraining the mind-stuff (Citta) from taking various forms (Vrittis)."

A sculpture of a Hindu yogi in the Birla Mandir, Delhi

Patanjali's writing also became the basis for a system referred to as "Ashtanga Yoga" ("Eight-Limbed Yoga"). This eight-limbed concept derived from the 29th Sutra of the 2nd book, and is a core characteristic of practically every Raja yoga variation taught today. The Eight Limbs are:

• 1. Yama (The five "abstentions"): non-violence, non-lying, non-covetousness, non-sensuality, and non-possessiveness.
• 2. Niyama (The five "observances"): purity, contentment, austerity, study, and surrender to god.
• 3. Asana: Literally means "seat", and in Patanjali's Sutras refers to the seated position used for meditation.
• 4. Pranayama ("Suspending Breath"): Prana, breath, "ayama", to restrain or stop. Also interpreted as control of the life force.
• 5. Pratyahara ("Abstraction"): Withdrawal of the sense organs from external objects.
• 6. Dharana ("Concentration"): Fixing the attention on a single object.
• 7. Dhyana ("Meditation"): Intense contemplation of the nature of the object of meditation.
• 8. Samadhi ("Liberation"): merging consciousness with the object of meditation.

In the view of this school, the highest attainment does not reveal the experienced diversity of the world to be illusion. The everyday world is real. Furthermore, the highest attainment is the event of one of many individual selves discovering itself; there is no single universal self shared by all persons.

Yoga and Samkhya

Main article: Samkhya

Patanjali systematized the conceptions of Yoga and set them forth on the background of the metaphysics of Samkhya, which he assumed with slight variations. In the early works, the Yoga principles appear along with the Samkhya ideas. Vyasa's commentary on the Yoga Sutras, also called the "Samkhyapravacanabhasya", brings out the intimate relation between the two systems.

Yoga agrees with the essential metaphysics of Samkhya, but differs from it in that while Samkhya holds that knowledge is the means of liberation, Yoga is a system of active striving, mental discipline, and dutiful action. Yoga also introduces the conception of God. Sometimes Patanjali's system is referred to as "Seshvara Samkhya" in contradistinction to Kapila's "Nirivara Samkhya". Bhagavad Gita

Main article: Bhagavad Gita

The Bhagavad Gita ('Song of the Lord'), uses the term yoga extensively in a variety of ways. In addition to an entire chapter ( dedicated to traditional yoga practice, including meditation, it introduces three prominent types of yoga:

• . Karma yoga: The yoga of action,
• . Bhakti yoga: The yoga of devotion,
• . Jnana yoga: The yoga of knowledge.

Madhusudana Sarasvati (b. circa 1490) divided the Gita into three sections, with the first six chapters dealing with Karma yoga, the middle six with Bhakti yoga, and the last six with Jnana (knowledge). Other commentators ascribe a different 'yoga' to each chapter, delineating eighteen different yogas.

Hatha Yoga

Main articles: Hatha yoga and Hatha Yoga Pradipika

Hatha Yoga is a particular system of Yoga described by Yogi Swatmarama, compiler of the Hatha Yoga Pradipika in 15th century India. Hatha Yoga differs substantially from the Raja Yoga of Patanjali in that it focuses on shatkarma, the purification of the physical body as leading to the purification of the mind (ha), and prana, or vital energy (tha). Compared to the seated asana, or sitting meditation posture, of Patanjali's Raja yoga, it marks the development of asanas (plural) into the full body 'postures' now in popular usage and, along with its many modern variations, is the style that many people associate with the word "Yoga" today. Modern, Westernised Yoga

In the West, the term yoga is typically associated with Hatha Yoga and its asanas (postures) or as a form of exercise.

Tantra

Main article: Tantra

Tantrism is a practice that is supposed to alter the relation of its practitioners to the ordinary social, religious, and logical reality in which they live. Through Tantric practice, an individual perceives reality as maya, illusion, and the individual achieves liberation from it.[95] Both Tantra & Yoga offer paths that relieve a person from depending on the world. Where Yoga relies on progressive restriction of inputs from outside; Tantra relies on transmutation of all external inputs so that one is no longer dependent on them, but can take them or leave them at will. They both make a person independent.[96] This particular path to salvation among the several offered by Hinduism, links Tantrism to those practices of Indian religions, such as yoga, meditation, and social renunciation, which are based on temporary or permanent withdrawal from social relationships and modes.[95]

As Robert Svoboda attempts to summarize the three major paths of the Vedic knowledge, he exclaims:

Because every embodied individual is composed of a body, a mind and a spirit, the ancient Rishis of India who developed the Science of Life organized their wisdom into three bodies of knowledge: Ayurveda, which deals mainly with the physical body; Yoga, which deals mainly with spirit; and Tantra, which is mainly concerned with the mind. The philosophy of all three is identical; their manifestations differ because of their differing emphases. Ayurveda is most concerned with the physical basis of life, concentrating on its harmony of mind and spirit. Yoga controls body and mind to enable them to harmonize with spirit, and Tantra seeks to use the mind to balance the demands of body and spirit.[96]

During tantric practices and studies, the student is instructed further in meditation technique, particularly chakra meditation. This is often in a limited form in comparison with the way this kind of meditation is known and used by Tantric practitioners and yogis elsewhere, but is more elaborate than the initiate's previous meditation. It is considered to be a kind of Kundalini Yoga for the purpose of moving the Goddess into the chakra located in the "heart", for meditation and worship.[97]

Goal of yoga

The goals of yoga are varied and range from improving health to achieving Moksha.[42] Within Jainism and the monist schools of Advaita Vedanta and Shaivism, the goal of yoga takes the form of Moksha, which is liberation from all worldly suffering and the cycle of birth and death (Samsara), at which point there is a realization of identity with the Supreme Brahman. In the Mahabharata, the goal of yoga is variously described as entering the world of Brahma, as Brahman, or as perceiving the Brahman or Atman that pervades all things.[98] For the bhakti schools of Vaishnavism, bhakti or service to Svayam bhagavan itself may be the ultimate goal of the yoga process, where the goal is to enjoy an eternal relationship with Vishnu.[99]