Now the centre where all these residual sensations are, as it were, stored up, is called the Muladhara, the root receptacle, and the coiled-up energy of action is Kundalini, "the coiled up". It is very probable that the residual motor energy is also stored up in the same centre, as, after deep study or meditation on external objects, the part of the body where the Muladhara centre is situated (probably the sacral plexus) gets heated. Now, if this coiled-up energy be roused and made active, and then consciously made to travel up the Sushumna canal, as it acts upon centre after centre, a tremendous reaction will set in. When a minute portion of energy travels along a nerve fibre and causes reaction from centres, the perception is either dream or imagination. But when by the power of long internal meditation the vast mass of energy stored up travels along the Sushumna, and strikes the centres, the reaction is tremendous, immensely superior to the reaction of dream or imagination, immensely more intense than the reaction of sense-perception. It is super-sensuous perception. And when it reaches the metropolis of all sensations, the brain, the whole brain, as it were, reacts, and the result is the full blaze of illumination, the perception of the Self.