Intoxicants are remarkable; they arouse us and incite us to action. This emotional excitement gives us pleasure and a greater belief in the intoxicant and the reality of the pleasure it provides. This primary self-consciousness is provided for by the brainstem and the limbic, or hedonic, system that act in tandem to regulate bodily functions concerned with consummatory and defensive behaviours. It is a value system; a system whose extensive connections adjust the response of hormones and the autonomic nervous system to emotional demands. It responds slowly, in seconds to minutes. Unlike the cortex, which has discrete functional regions designed to deal with signals from the exterior, the limbic-brainstem loop system has evolved to match the body. Heart rate, sweating, appetite, digestion, sex and sleep are all regulated by this system; it deals solely with the interior and maintains our state of well-being. This is homeostasis, the mechanism that maintains stability within the physiological systems and holds all parameters of our internal milieu within limits that allow us to survive....