If the meaning of yoga is understood as the practice of nirodha (mental control), then its goal is "the unqualified state of niruddha (the perfection of that process)", according to Baba Hari Dass. In that context, "yoga (union) implies duality (as in joining of two things or principles); the result of yoga is the nondual state", and "as the union of the lower self and higher Self. The nondual state is characterized by the absence of individuality; it can be described as eternal peace, pure love, Self-realization, or liberation."
According to Crangle, some researchers have favoured a linear theory, which attempts "to interpret the origin and early development of Indian contemplative practices as a sequential growth from an Aryan genesis",[note 4] just like traditional Hinduism regards the Vedas to be the ultimate source of all spiritual knowledge.[note 5] Thomas McEvilley favors a composite model where pre-Aryan yoga prototype existed in the pre-Vedic period and its refinement began in the Vedic period.
^ World Health Organization.Constitution of the World Health Organization as adopted by the International Health Conference, New York, 19–22 June 1946; signed on 22 July 1946 by the representatives of 61 States (Official Records of the World Health Organization, no. 2, p. 100) and entered into force on 7 April 1948. In Grad, Frank P. (2002). "The Preamble of the Constitution of the World Health Organization". Bulletin of the World Health Organization. 80 (12): 982.
The Maitrayaniya Upanishad, likely composed in a later century than Katha and Shvetashvatara Upanishads but before Patanjali's Yoga Sutra, mentions sixfold yoga method – breath control (pranayama), introspective withdrawal of senses (pratyahara), meditation (dhyana), mind concentration (dharana), philosophical inquiry/creative reasoning (tarka), and absorption/intense spiritual union (samadhi).
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.