There is tangible energy in the Human system.It courses from Agna Chakra(center of brain down to the spine Up to the Mooladhara Chakra(coccyx).
All this emery normally flows down for digestion,elimination,and excretion and reproduction.This down flowing energy is called Samana in Sanskrit language.Man is occupied almost all time with this energy.
When there is creativity,spiritual activity and yoga energy starts to flow upwards.This up flowing energy is called Prana in Sanskrit language.
On reversing the path of inhalation upwards in pranayama(breathing practice great energy is released in reversing samana and energy gets stored mainly in brain and spinal cord.
Thus gradually the pull of the senses gets released from the consciousness and pure consciousness starts to manifest.