The body is a closed system for many reasons. Like any closed organic system it has an internal and external environment. The internal environment is intensely monitored and controlled. It has been called Nature’s clean room in which quadrillions of essential chemical' and electrical transactions take place every second in its more than 7 trillion cells. The totality of this living activity is called metabolism. Any deviation whatsoever in pressure, concentration, rate of reaction, pH or multiple other considerations immediately triggers a cascade of rectifying activity to return to the ideal. Only when the ideal internal environment is preserved can health be optimized. Homeostasis is the tendency toward a stable equilibrium between independent elements, especially as maintained by physiological processes. When homeostasis is disturbed, it is signaled to the skin and the Bessana scanner can detect the signal.