In order to understand a subject clearly, certain general laws, or principles, must be seen and admitted. And here we assume, as a general truth, that health in the human body is normal heavenly order on the physical plane of life, and that any disturbance of that order exposes the man to destructive influences, which are evil and infernal in their character. Above the natural and physical plane, and resting upon it, while man lives in this world, is the mental and spiritual plane, or degree of life. This degree is in heavenly order when the reason is clear, and the appetites and passions under its wise control. But, if, through any cause, this fine equipoise is disturbed, or lost, then a way is opened for the influx of more subtle evil influences than such as invade the body, because they have power to act upon the reason and the passions, obscuring the one and inflaming the others. MENTAL DISTURBANCES. We know how surely the loss of bodily health results in mental disturbance. If the seat of disease be remote from the brain, the disturbance is usually slight; but it increases as the trouble comes nearer and nearer to that organ, and shows itself in multiform ways according to character, temperament or inherited disposition; but almost always in a predominance of what is evil instead of good. There will be fretfulness, or ill-nature, or selfish exactions, or mental obscurity, or unreasoning demands, or, it may be, vicious and cruel propensities, where, when the brain was undisturbed by disease, reason held rule with patience and loving kindness. If the disease which has attacked the brain goes on increasing, the mental disease which follows as a consequence of organic disturbance or deterioration, will have increased also, until insanity may be established in some one or more of its many sad and varied forms. INSANITY. It is, therefore, a very serious thing for a man to take into his body any substance which, on reaching that wonderfully delicate organ--the brain, sets up therein a diseased action; for, diseased mental action is sure to follow, and there is only one true name for mental disease, and that is _insanity_. A fever is a fever, whether it be light or intensely burning; and so any disturbance of the mind's rational equipoise is insanity, whether it be in the simplest form of temporary obscurity, or in the midnight of a totally darkened intellect.