Disease routinely lies at the end of a three-part chain that goes: irritation or sub-clinical malnutrition, enervation, toxemia. Irritations are something the person does to themselves or something that happens around them. Stresses, in other words.

Mental stressors include strong negative emotional states such as anger, fear, resentment, hopelessness, etc. Behind most diseases it is common to find a problematic mind churning in profound confusion, one generated by a character that avoids responsibility. There may also be job stress or ongoing hostile relationships, often within the family.

Indigestible foods and misdigestion are also stressful irritations, as are mild recreational poisons such as "soft" drugs, tobacco and alcohol. Opiates are somewhat more toxifying, primarily because they paralyze the gut and induce profound constipation. Stimulants like cocaine and amphetamines are the most damaging recreational drugs ; these are highly toxic and rapidly shorten life.

Repeated irritations and/or malnutrition eventually produce enervation. The old-time hygienists defined enervation as a lack of or decline in an unmeasurable phenomena, "nerve energy." They viewed the functioning of vital organs as being controlled by or driven by nerve force, sometimes called life force or élan vital. Whatever this vital force actually is, it can be observed and subjectively measured by comparing one person with another. Some people are full of it and literally sparkle with overflowing energy. Beings like this make everyone around them feel good because they somehow momentarily give energy to those endowed with less. Others possess very little and dully plod through life.

As vital force drops, the overall efficiency of all the body's organs correspondingly decline. The pancreas creates less digestive enzymes; the thymus secretes less of its vital hormones that mobilize the immune system; the pituitary makes less growth hormone so the overall repair and rebuilding of cells and tissues slows correspondingly; and so forth. It does not really matter if there is or is not something called nerve energy that can or cannot be measured in a laboratory. Vital force is observable to many people. However, it is measurable by laboratory test that after repeated irritation the overall functioning of the essential organs and glands does deteriorate.

Enervation may develop so gradually that it progresses below the level of awareness of the person, or times of increased enervation can be experienced as a complaint--as a lack of energy, as tiredness, as difficulties digesting, as a new inability to handle a previously-tolerated insult like alcohol.

Long-term consumption of poor-quality food causes enervation. The body is a carbon/oxygen engine designed to run efficiently only on highly nutritious food and this aspect of human genetic programming cannot be changed significantly by adaptation. Given enough generations a human gene pool can adapt to extracting its nutrition from a different group of foods. For example, a group of isolated Fijians currently enjoying long healthy lives eating a diet of seafoods and tropical root crops could suddenly be moved to the highlands of Switzerland and forced to eat the local fare or starve. But most of the Fijians would not have systems adept at making those enzymes necessary to digest cows milk. So the transplanted Fijians would experience many generations of poorer health and shorter life spans until their genes had been selected for adaptation to the new dietary. Ultimately their descendants could become uniformly healthy on rye bread and dairy products just like the highland Swiss were.

However, modern industrial farming and processing of foodstuffs significantly contributes to mass, widespread enervation in two ways. Humans will probably adjust to the first; the second will, I'm sure, prove insurmountable. First, industrially processed foods are a recent invention and our bodies have not yet adapted to digesting them. In a few more generations humans might be able to accomplish that and public health could improve on factory food. In the meanwhile, the health of humans has declined. Industrially farmed foods have also been lowered in nutritional content compared to what food could be. I gravely doubt if any biological organism can ever adapt to an overall dietary that contains significantly lowered levels of nutrition. I will explain this more fully in the chapter on diet.