In the introduction to his classic book on yoga "Light on Yoga" B.K.S. Iyengar offers the following thoughtful and cogent comment on the definition of "Yoga".

B.K.S. Iyengar

What is Yoga?

The word Yoga is derived from the Sanskrit root yuj meaning to bind, join, attach and yoke, to direct and concentrate one's attention on, to use and apply. It also means union or communion. It is the true union of our will with the will of God. 'It thus means,' says Mahadev Desai in his introduction to the Gita according to Gandhi, 'the yoking of all the powers of body, mind and soul to God; it means the disciplining of the intellect, the mind, the emotions, the will, which that Yoga presupposes; it means a poise of the soul which enables one to look at life in all its aspects evenly.'

Yoga is one of the six orthodox systems of Indian philosophy. It was collated, co-ordinated and systematised by Patanjali in his classical work, the Yoga Sutras, which consists of 185 terse aphorisms. In Indian thought, everything is permeated by the Supreme Universal Spirit (Paramatma or God) of which the individual human spirit (jivatma) is a part. The system of yoga is so called because it teaches the means by which the jivatma can be united to, or be in communion with the Paramatma, and so secure liberation (moksa).

One who follows the path of Yoga is a yogi or yogin.

In the sixth chapter of the Bhagavad Gita, which is the most important authority on Yoga philosophy, Sri Krishna explains to Arjuna the meaning of Yoga as a deliverance from contact with pain and sorrow. It is said:

'When his mind, intellect and self (ahamkara) are under control, freed from restless desire, so that they rest in the spirit within, a man becomes a Yukta -- one in communion with God. A lamp does not flicker in a place where no winds blow; so it is with a yogi, who controls his mind, intellect and self, being absorbed in the spirit within him. When the restlessness of the mind, intellect and self is stilled through the practice of Yoga, the yogi by the grace of the Spirit within himself finds fulfilment. Then he knows the joy eternal which is beyond the pale of the senses which his reason cannot grasp. He abides in this reality and moves not therefrom. He has found the treasure above all others. There is nothing higher than this. He who has achieved it, shall not be moved by the greatest sorrow. This is the real meaning of Yoga -- a deliverance from contact with pain and sorrow.'

As a well cut diamond has many facets, each reflecting a different colour of light, so does the word yoga, each facet reflecting a diferent shade of meaning and revealing different aspects of the entire range of human endeavour to win inner peace and happiness.

The Bhagavad Gita also gives other explanations of the term yoga and lays stress upon Karma Yoga (Yoga by action). It is said: 'Work alone is your privilege, never the fruits thereof. Never let the fruits of action be your motive; and never cease to work. Work in the name of the Lord, abandoning selfish desires. Be not affected by success or failure. This equipoise is called Yoga.'

Yoga has also been described as wisdom in work or skilful living amongst activities, harmony and moderation. 'Yoga is not for him who gorges too much, nor for him who starves himself. It is not for him who sleeps too much, nor for him who stays awake. By moderation in eating and in resting, by regulation in working and by concordance in sleeping and waking, Yoga destroys all pain and sorrow.'

The Kathopanishad describes Yoga thus: 'When the senses are stilled, when the mind is at rest, when the intellect wavers not-then, say the wise, is reached the highest stage. This steady control of the senses and mind has been defined as Yoga. He who attains it is free from delusion.'

In the second aphorism of the first chapter of the Yoga Sutras, Patanjali describes Yoga as 'chitta vrtti nirodhah'. This may be translated as the restraint (nirodhah) of mental (chitta) modifications (vrtti) or as suppression (nirodhah) of the fluctuations (vrtti) of consciousness (chitta). The word chitta denotes the mind in its total or collective sense as being composed of three categories: (a) mind (manas, that is, the individual mind having the power and faculty of attention, selection and rejection; it is the oscillating indecisive faculty of the mind); (b) intelligence or reason (buddhi, that is, the decisive state which determines the distinction between things) and (c) ego (ahamkara, literally the I-maker, the state which ascertains that 'I know').

The word vrtti is derived from the Sanskrit root vrt meaning to turn, to revolve, to roll on. It thus means course of action, behaviour, mode of being, condition or mental state. Yoga is the method by which the restless mind is calmed and the energy directed into constructive channels. As a mighty river which when properly harnessed by dams and canals, creates a vast reservoir of water, prevents famine and provides abundant power for industry; so also the mind, when controlled, provides a reservoir of peace and generates abundant energy for human uplift.

The problem of controlling the mind is not capable of easy solution, as borne out by the following dialogue in the sixth chapter of the Bhagavad Gita. Arjuna asks Sri Krishna:

'Krishna, you have told me of Yoga as a communion with Brahman (the Universal Spirit), which is ever one. But how can this be permanent, since the mind is so restless and inconsistent? The mind is impetuous and stubborn, strong and wilful, as difficult to harness as the wind.' Sri Krishna replies: 'Undoubtedly, the mind is restless and hard to control. But it can be trained by constant practice (abhyasa) and by freedom from desire (vairagya). A man who cannot control his mind will find it difficult to attain this divine communion; but the self-controlled man can attain it if he tries hard and directs his energy by the right means.'