This section is from the "Impaired Health: Its Cause And Cure" (Volume 1) book, by John H. Tilden. Also available from Amazon: Impaired health its cause and cure: A repudiation of the conventional treatment of disease
The simplest definition for man is that he is a digestive apparatus. Food is taken into the stomach and bowels, where it is dissolved--brought to the liquid state--and then absorbed into the circulation and distributed throughout the body. From this circulating medium the cells of the various tissues of the body select the food elements required to do their work.
This process is called nutrition. When nutrition is going on normally, the standard of health is normal. Any influence that decreases, increases, or prevents nutrition is disease-producing, or, in better words, lowers the health standard.
The detrimental influences of nutrition may begin in the stomach; yet, farther back, the chewing may be imperfect; and, farther back still, the food may be imperfectly prepared.
The common cause of gastro-intestinal indigestion is enervation and overeating.
Nerve energy is required to digest food; nerve energy is required to keep up secretions and excretions; nerve energy is required to prepare enzymes for digesting our food intake and keeping up a normal resistance to environmental influences as well as those that are autogenerated.
When this nerve energy is up to the standard, we are poised--or balanced, as it were, with our environments--and we can eat a maximum amount of food, and take care of it. This being true, it should be obvious to those who care to reason that any influence which uses up nerve energy lowers the digestive powers of the body, and that an amount of food which can be utilized when the nerve energy is up to standard must necessarily be too much when the energy is used up in work, play, or sensual indulgence.
It should be obvious to any reasoning mind that a full dinner taken into a tired body cannot be digested properly; that a full meal, or any meal at all, eaten by one in great mental anguish over some great trouble, cannot be digested. And, when food is not digested, it becomes a poison.
It should never be forgotten that food taken into the body is man's food or bane. There is no neutral ground. This explains why enough food at one time may be too much at another time.
When food is taken into the stomach in too great quantities--more than the digestive secretions (enzymes) can dissolve--digestion takes place on the outside of the ingested meal, and continues until the digestive energy is used up. As fast as the food is liquefied, it passes out through the pylorus, where, in the duodenum, it meets with other enzymes and is further fitted for absorption. Absorption is going on as fast as the food is liquefied enough to fit it for absorption, which is in a very short time after leaving the stomach.
When enzymic fermentation--digestion---ends, bacterial fermentation of the remainder of the food in the stomach begins. One or the other of these fermentative processes must go on, or eating will end; for, unless the food is liquefied, it cannot get out of the stomach and bowels.