The human body is a marvellous vehicle for housing many subtle bodies. Some of these subtle bodies contain chakras or force centres, which can also be felt in the physical body, but only observed in certain subtle bodies. The easiest subtle body to observe the chakra system is in the etheric body as it overlaps into the astral body. In the physical body we can feel the pulse of the chakra system in the spine, and other locations of the chakras.
Special centres from where groups of sensory motor nerves arise are situated in the spinal column. The energy from these nerves pervades the entire body to rejuvenate it with the vital life force. The nerve centres are connected with seven centres of vital energy in the body called force centres or chakras. Some modern writers have identified the subtle spinal channels of Ida, Pingala and Sushumna as the spinal cord with the sympathetic nerve chains, and the chakras or force centres as the nerve centres or plexi of the body.
This is not quite correct, as these structures are not perceived without special meditation techniques, neither can their activity be equated with their physical structure. It is rather like the filaments of an electric light bulb that uses a material wire circuit, but the bulb does not light up until the electricity flows through it.
When the luminescent current of the vital life force flows through the nerve centres of the body, in association with the endocrine glands, they become luminous to the subtle sight, and shine with exquisite, colours that adopt a circular shape. Most illustrations of these force centres in the body are shown depicted in symbolical pictorial shapes such as spheres, vortices and wheels. They do, in fact, resemble these actual shapes, but since they are not physical objects, it is not possible to give a standard, exact description. Many people describe these chakras in different ways for this very reason.