
There is another difference between Patanjali's system of RajYoga and traditional system of Hatha Yoga .The authors of hatha Yoga text were very much aware of the difficulty in controlling the fluctuations of the mind .You may manage it for sometime ,but still you will not be able to succeed all time. So they adopted another method.
The Hatha Yoga text states very clearly that by controlling the pranas,the mind is automatically controlled.It seems that prana and mind exert an influence on each other . When the pranas are restless ,it affects the mind and vice versa. Some people find it easier to control the mind than to control the prana. Few people succeed but most of them cannot .The more they try ,the more the split grows .
The author of Hatha Yoga says " Don't worry about the mind, ignore it and practice pranayama "
By practicing pranayama correctly , the mind is automatically conquered. However ,the effects of pranayama are not so simple to manage .It creates extra heat in the body ,it awakens some of the dormant centers in the brain ,it can alter the production of sperm and testosterone .It lowers the respiratory rate and change the brain wave patterns. When these changes take place , you may not be able to handle it .Therefore , hatha yoga says that the shatkarmas must be practiced first.
The purpose of emphasizing shatkarma is to prepare a base for the higher practices of pranayama .Shatkarma purifies the whole system and removes blockages on the path of ida and pingala .When there are no mental or vital blockages ,the breath in both the nostrils flows systematically .When the left nostril flows it means ida is active and the mind is dominant . When the right nostril flows it means the breath in pingala is active and the pranas are predominating . The flow of the breath in alternate nostril indicates the state of balance of the sympathetic and parasympathetic nervous systems .
If ida is flowing and you are meditating ,you will go to sleep and your brain will produce delta waves .If the right nostril is flowing and you are trying to meditate ,your brain will produce beta waves and you will be thinking many thoughts at the same time .When both the nostrils are flowing equally ,that means sushumna is flowing .When sushumna flows you can meditate without any difficulty .Awakening of sushumna ,making sushumna nadi flow ,is the most important process in yoga which precedes kundalini awakening .