Breathing is the most natural act a person performs and is central to the practice of swara yoga. Everyone breathes day and night. It appears to be an ordinary and simple act, yet it has a deep significance. It is mysterious, too. Most people imagine an equal volume of air is inhaled and exhaled through both nostrils. This is not quite true. The flow of air through the nostrils is never continually the same. Generally, a greater volume of air flows in and out through one nostril rather than the other. The predominant nostril changes with time, as well.
Swara is considered a manifestation of the soul. It's worth has been stressed in various texts. Some texts state that the entire Vedas and shastras (scriptures) constitute swara. What does this mean? Through swara prana, shakti circulates in the human body. It is by this prana shakti that one gains all knowledge and performs all actions. Without prana or vital energy, this body is without life. It is what keeps this body conscious, active, and capable of assimilating knowledge. Prana or vital energy is not only the guardian of the physical body but also serves as a vehicle for reaching the higher spiritual planes. There are many esoteric uses for this vital energy that flows with every act of breathing.
In the various hatha yoga postures and in meditation, breathing is of great importance. It is from the bow-string of breath that the arrow of the mind is released in order to penetrate the soul. Prana or vital energy is not only the guardian of the physical body but also serves as a vehicle for reaching the higher spiritual planes. There are many esoteric uses for this vital energy that flows with every act of breathing
Current medical science has no explanation to offer for this phenomenon. Yet, since ancient times, the tradition and practice of swara shastra - swara yoga - has existed in India. Without knowledge of swara shastra even astrology is incomplete. The scripture states that the person who has mastered swara yoga is considered a supreme yogi: