What this book is based on
The answers, comments, observations, and insights in this book are based on the principles of Natural Hygiene, and on common sense, logic, and much independent and considered thought.
Natural Hygiene is that branch of biology which investigates and applies the conditions upon which life and health depend, and the means by which health is rebuilt and maintained when it has been lost or impaired; it is the study of "the science of health". (And it is the branch of biology that you hear very little about if anything, and with good reason; restoring health through natural methods makes plenty of sense, but not plenty of dollars. In fact, it is at odds with other areas of health that are very financially profitable.)
Natural Hygiene may be further defined as being the science and art of restoring and preserving health by those substances and influences that have a normal relation to life: food we're designed to eat, sufficient nutrition, pure water, strong enough sunshine, rest, sleep, relaxation, appropriate amounts of physical activity, play, comfortable environment, and positive social relationships; it is the scientific application of the principles of Nature in the preservation and restoration of health. Natural Hygiene covers the total needs of humans, and not merely a few of their requirements. It is neither a practice of medicine, a healing art, nor a system of therapeutics. It offers no cures, does not pretend to cure, and in fact strives to dispel the popular notion of cures. Instead, Natural Hygiene emphasizes that adherence to its principles, which are based on the Laws of Nature, permits the body to heal itself.
It should also be noted that there are no substitutes for some of the above requirements, like sleep and physical activity, and this is lucky because we have a lot of control over things like sleep and exercise. But other requirements like sunshine (for D), vitamin B12, and nutritious food, may be hard to come by in our modern environment for various reasons. And when this is the case, this is when the science and art of restoring and preserving health looks to "non-natural" practices in order to provide what we need for optimal health, and doing so is not a violation of healthful living; on the contrary, it is allowing us to be as healthy as we can be in today's unnatural environment it comes under the heading of doing the best we can under the circumstances.