What is often referred to as Classical Yoga, Astanga (Yoga of eight limbs), or Raja Yoga is mainly the type of Yoga outlined in the highly influential Yoga Sutras of Patanjali. The origins of the Classical Yoga tradition are unclear, though early discussions of the term appear in the Upanishads. The name "Rāja yoga" (yoga of kings) originally denoted the ultimate goal of yoga, samadhi, but was popularised by Vivekananda as a common name for Ashtanga Yoga,[note 19] the eight limbs to be practised to attain samadhi, as described in the Yoga Sutras. Yoga is also considered as one of the orthodox philosophical schools (darsanas) of Hinduism (those which accept the Vedas as source of knowledge).
The meaning of health has evolved over time. In keeping with the biomedical perspective, early definitions of health focused on the theme of the body's ability to function; health was seen as a state of normal function that could be disrupted from time to time by disease. An example of such a definition of health is: "a state characterized by anatomic, physiologic, and psychological integrity; ability to perform personally valued family, work, and community roles; ability to deal with physical, biological, psychological, and social stress". Then in 1948, in a radical departure from previous definitions, the World Health Organization (WHO) proposed a definition that aimed higher: linking health to well-being, in terms of "physical, mental, and social well-being, and not merely the absence of disease and infirmity". Although this definition was welcomed by some as being innovative, it was also criticized as being vague, excessively broad and was not construed as measurable. For a long time, it was set aside as an impractical ideal and most discussions of health returned to the practicality of the biomedical model.