What is Yoga? Nowadays it is presented and understood wrongly all over the world. It seems that both Yoga 'gurus' and general people are confused about Yoga. Often Yoga 'gurus' present physical exercise (Asana) and breathing exercise (Pranayama) as Yoga. And general people assume accordingly. It is true that 'Asana' and 'Pranayama' are part of the means of Yoga but not the Yoga in itself. To be clear about Yoga we should take the 'Patanjali Yoga Sutra' as a source document because the 'Patanjali Yoga Sutra' is the only authentic document of the Science of Yoga.
According to 'Patanjali Yoga Sutra 'Absence of inclination is the Yoga'. (Sutra no. 1) That is, when our mind become free of inclination that is the state of Yoga. Sutra no. 2 states— 'At that state the person remains on original form'. That is, the state of Yoga is the original state of the person. Sutra no. 3 states— 'In other state the person resembles as inclination'. That is, except the state of Yoga in all other state of mind the person resembles as inclination; not as the original person. There are altogether 195 Sutras in 'Patanjali Yoga Sutra' but these three Sutras are the crux of the 'Science of Yoga'. All other Sutras of the 'Patanjali Yoga Sutra' are explanation of these three Sutras. After pondering on these three Sutras and rest of all Sutras we can conclude that the science of Yoga is 'Science of Life', that is, 'Science of Body' and 'Science of Mind'. That is, the science of Yoga is 'The Science of Real Spirituality'. Life is represented by the body and the body is inclination free in itself. But the mind can be inclined when we remain out of Yoga state or Original state or the State of the Body. So to be disinclined we should return to the State of the Body. For that purpose we should heed the body's tone. When mind becomes pure equally as the body then we become disinclined completely and remain on our original form. This is the crux of the lessons of the Yoga.
To return to the original form there presented eight-pointed means in 'Patanjali Yoga Sutra'. These eight means are : 1) Yama, 2) Niyama, 3) Asana, 4) Pranayama, 5) Pratyahara, 6) Dharana, 7) Dhyana and 8) Samadhi. Among these eight Yama is code of conduct in relation to others; and Niyama is code of conduct in relation to self. If anybody follows these two thoroughly s/he certainly returns toward her/his common sense, that is, to the tone of the body and remains on original form. So the Yama and the Niyama are the crux of the eight points. Without following Yama and Niyama nobody can attain the state of Yoga.
Asana and Pranayama are physical and breathing exercises. Only doing Asana and Pranayama nobody can attain the state of Yoga. Pratyahara is in actual sense part of the Niyama. Dharana, Dhyana and Samadhi are series wise concentration exercises. These concentration exercises can generate relaxation for the body and mind temporarily but can't make the mind disinclined automatically. So except Yama and Niyama other six are not inner purifier of the mind but they can assist in purifying process by calming down the mind temporarily. To purify the mind thoroughly it is necessary to think rationally following the body's tone. And while thinking rationally, one should follow Yama and Niyama consciously because while following Yama and Niyama the person should learn to be sincere to the self and the others. Conscious effort with rational thinking is necessary to return toward original form of the person, that is, the state of the Yoga.