Yoga is the way to achieve a pure body and a pure mind- the basic requirements of philosophy. In Yoga the ultimate unchanging perfect Purusha is termed god and if meditated upon he takes other purushas towards salvation. Patanjali`s Yogasutra is regarded as the main source of codification of yoga. Yoga is seen as a means to both physiological and spiritual mastery. Yoga as a combination of exercises and meditation has been practiced for over 5,000 years. The main branches of Yoga, according to the Bhagwad Gita or `Song of the Lord`, have been classified as: Karma Yoga, Jnana Yoga, Bhakti Yoga and Raja Yoga. It gives the methods by which the body and the mind can be made to achieve vidya.

The basis of Yoga is believed to be a network of about 7000 nadis or small nerves. According to Yoga the human body consists of two parts, the upper body (torso, arms and head) and the lower body (legs and feet). The centre of the human body lies at the base of the cerebro-spinal (Brahmadanda or Merudanda) column. This Merudanda has six plexus (chakras), which are the invisible to the human eye but are visible through yoga. The body is considered to be the instrument for the expression of spiritual life.

Raja Yoga, also known as `royal yoga`, `royal union`, Classical Yoga or just Yoga, is one of the six orthodox (astika) schools of Hindu philosophy, delineated by Patanjali in his Yoga Sutras. Raja Yoga is concerned primarily with the cultivation of mind using meditation (dhyana) to foster one`s acquaintance with reality and ultimately liberation. The term Raja Yoga is a retronym (a word introduced because an existing term has become inadequate, is no longer unique, or is otherwise inappropriate or misleading), introduced during the 15th century Hatha Yoga Pradipika to differentiate the school based on the Yoga Sutras from the new current Hatha Yoga. The term was later used to describe the exclusively unrelated meditation practice of the Brahma Kumaris, demanding the focus of one`s mind and surrender to a channelled entity they believe to be the Supreme Soul.

Raja Yoga is sometimes referred to as Ast?nga (eight-limbed) yoga, because there are eight aspects to the path to which one must attend.

Concept of Yoga philosophy
The fundamental concept of yoga is mind and its relationship with the human body. A normal human is always inundated with outside thoughts and desires and cravings for the wrong, the unknown and material pleasure. These avarices are sure to bring one to completed destruction. Thus, by maintaining a state of celibacy and asceticism, one will be successful to curb his/her desires and gradually obtain a serenity of mind. The body though can only be sanctified by practicing yoga and following the set of rules stated by Patanjali. Yogic practice can bring about a `seedless` state of mind, where it will be able to focus on the right path.

Eight limbs of Ashtanga Yoga
Yoga is frequently referred to as Ashtanga yoga, due to its facets of an eight-fold path to salvation. In order to achieve success, one must abide by these eight rules. The concepts are: Yama, Niyama, Pranayama, Pratyahara, Dharana, Dhyana and Samadhi