For instance, if the cell be hungry, thirsty, cold or in pain, it telegraphs these sensations to headquarters in the brain or spinal cord and from there directions necessary to comply with the needs of the cell are sent forth in the form of nerve impulses to the centers controlling the circulation, the food and heat supply, the means of protection, etc. This circuit of communication from the cell over the afferent nerves to the nerve centers in the brain or spinal cord, and from these centers over the efferent nerves back to the cell or to other cells is called the reflex arc. Let us use an illustration: Suppose the fingers come in close contact with a hot iron. The cells in the finger tips experience a sensation of burning pain. At once this sensation is telegraphed over the afferent nerves to the nerve centers in the brain or spinal cord. In response to this call of distress the command comes back over the efferent nerve filaments: "Withdraw the fingers!" At the same time the impulse to withdraw the fingers is sent over the motor nerves to the muscles and ligaments which control the movements of the hand. If the means of communication between the different parts of the organism are obstructed or cut off entirely, the individual cell is bound to deteriorate and to die, just like a person lost in a barren wilderness and cut off from his fellowmen must perish. In warfare it is a well-known fact that if one of the contending armies succeeds in cutting off the telegraphic communication of the other army with its headquarters, the activities of that other army are seriously handicapped. So the waste materials in the system, the disease taints, narcotic and alcoholic poisons, etc., obstruct the nerve passages, and thus interfere with the functions of the cell by cutting off its means of communication. What has been said will serve to elucidate and emphasize the necessity of perfect cleanliness, inside as well as outside of the body. It justifies the dictum of Kuhne, the apostle of Nature Cure: "Cleanliness is Health." Anything that in any way interferes with or obstructs the circulation of vital fluids and nerve currents in the system is bound to create the abnormal conditions and functions which constitute disease. When the morbid encumbrances and obstructions in the organism have reached the point where they seriously interfere with the nourishment, drainage and nerve supply of the cells, the latter cannot perform their activities properly, nor can they rid themselves of the impediment. They may be compared to people who are forced to live in bad, unwholesome surroundings and who cannot do their best work under these unfavorable conditions from which they cannot escape. In this way originates chronic disease, which means that the cells have become incapable of arousing themselves to acute eliminative effort in the form of inflammatory febrile reactions.