The Yogi conceives of several centres, beginning with the Mulâdhâra, the basic, and ending with the Sahasrâra, the thousand-petalled Lotus in the brain. So, if we take these different plexuses as representing these lotuses, the idea of the Yogi can be understood very easily in the language of modern physiology. We know there are two sorts of actions in these nerve currents, one afferent, the other efferent; one sensory and the other motor; one centripetal, and the other centrifugal. One carries the sensations to the brain, and the other from the brain to the outer body. These vibrations are all connected with the brain in the long run. Several other facts we have to remember, in order to clear the way for the explanation which is to come. This spinal cord, at the brain, ends in a sort of bulb, in the medulla, which is not attached to the brain, but floats in a fluid in the brain, so that if there be a blow on the head the force of that blow will be dissipated in the fluid, and will not hurt the bulb. This is an important fact to remember. Secondly, we have also to know that, of all the centres, we have particularly to remember three, the Muladhara (the basic), the Sahasrara (the thousand-petalled lotus of the brain) and the Manipura (the lotus of the navel).