By systematically restraining the prana (breath), the nadis and chakras are purified, allowing the prana to enter the sushumna.

"As long as the breath is restrained in the body, the mind is devoid of thought, and the gaze is centered between the eye..."

"Non-violence, truth, non-stealing, continence, forgiveness, endurance, compassion, humility, moderate diet, and cleanlin..."

"When the mind ceases to be fickle and is united by fixing it in nada, it becomes immobile like a wingless bird."

"The system has been designed for the people of Kali Yuga; Hatha Yoga commences with purification of the body."