When mind changes into will, the nerve currents change into a motion similar to electricity, because the nerves have been proved to show polarity under the action of electric currents. This shows that when the will is transformed into the nerve currents, it is changed into something like electricity. When all the motions of the body have become perfectly rhythmical, the body has, as it were, become a gigantic battery of will. This tremendous will is exactly what the Yogi wants.
understanding pranayama
