“Liberation can be accomplished by that pranayama which is attained by disjoining the course of inspiration and expiration.”
– Patanjali
“Offering inhaling breath into the outgoing breath, and offering the outgoing breath into the inhaling breath, the yogi neutralizes both these breaths; he thus releases the life force from the heart and brings it under his control.” 26-2 The interpretation is: “The yogi arrests decay in the body by an addition of life force, and arrests the mutations of growth in the body by apan (eliminating current). Thus neutralizing decay and growth, by quieting the heart, the yogi learns life control.” – Krishna quoted in the Bhagavad Gita, interpretation by Pramahansa Yogananda