Now we shall see why breathing is practised. In the first place, from rhythmical breathing comes a tendency of all the molecules in the body to move in the same direction. 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. This is, therefore, a physiological explanation of the breathing exercise. It tends to bring a rhythmic action in the body, and helps us, through the respiratory centre, to control the other centres. The aim of Prânâyâma here is to rouse the coiled-up power in the Muladhara, called the Kundalini.