Yoga is the supreme gift of India to the world at large. Yoga does not quarrel with science; it supplements it. Yoga is a methodical way to attain perfection, through the control of the different elements of human nature - both physical and psychical.
Yoga is the supreme science of contacting reality. It is perfection in action. It is equanimity of attitude. It is perfect peace. Yoga is union with God.
Yoga is not a thing merely to be heard. Yoga is a thing that has to be assimilated and put into practice in daily life. The practice of yoga enables one to realise unity with the whole world. It is living in tune with God.
Yoga is abiding by the principles of truth and avoiding the path of untruth. Yoga is a science which is meant for the study of the reflective. It is for those who are convinced that the world of the senses has nothing substantial to offer.
Yoga is a process of continuous transformation. The inner perfection of Self-realisation can only come to be revealed by experience. This happens only progressively. The transformation of one's personality is achieved through stages.
As you advance in yoga, the ego is progressively replaced by the spirit. It is through this that the will of God works. By the practice of yoga, the sadhaka (seeker) is freed from the tyranny of the lower mind and he becomes divine. At a later stage the transformation takes the shape of a progressive unfoldment of the spirit.
A preceptor or guru is indispensable for the practice of yoga. The aspirant should be humble, simple, gentle, refined, tolerant, merciful and kind. You will not have success in yoga if you have desire to get psychic powers. Yoga does not consist of sitting cross-legged for six hours, nor in stopping the heart-beat, nor in getting buried in the ground for a week or a month.