This section of the book is from the "Handbook of Nature Cure Volume One: Nature Cure vs. Medical Science" book, by John L. Fielder.
Warmth is always generated by fermentation; the more violent the fermentation, the greater the increase in temperature. This warmth is produced by the friction of the masses against each other and against the body, and likewise by the process of fermentation itself, and the changes in the fermentation accompanying it.
Under proper conditions, every process of fermentation can be caused to retrogress upon its own course; and this applies to all the changes in form caused by such fermentation. This is a fact which has hitherto never been properly understood. But I need merely remind you how Nature melts ice into water, how the latter is transformed by great warmth and wind into vapour, and how this, vaporised and invisible, then again condenses and appears to the eye as cloud, pouring down as rain, snow, or hail to refill the rivers and streams, and by severe cold to be again congealed to ice. And all this has been brought about by differences in temperature. Constantly increasing warmth has brought about the changes in the state of the water, and increasing cold has caused a retrogression of the process. A similar thing takes place in the development of foreign substances in the body, and similar conditions produce a retrogressive metamorphosis and expel them from the system.
What the exact nature of the little vegetable organisms, the ferments, is, is of but secondary interest for us; but it is important to know that they can develop only where there is suitable soil, that is, where substances are present which are ready to pass into decomposition.
Where such are present, only the right kind of weather or some other exciting cause is needed to give rise to fermentation. Such fermentation is also set up in the human system at the first instigation, as there is soon as sufficient foreign matter ready to pass into decay or decompose. Such chance exciting cause is a change of weather (hence what are popularly known as colds); the consumption of food especially apt to ferment, which remains longer than it should in the digestive canal; anger, fright, strong emotion, a shock, etc.
My observations show that fermentation always commences in the abdomen. Often it only causes diarrhea and is got rid of; but frequently, particularly where there is constipation, the system does not succeed in its attempt at speedy self-help and fermentation continues, especially in those parts where foreign matter has accumulated.
The case is like that of a bottle where the bottom admits of no outlet, and the fermenting matter pushes its way upwards to the mouth. Thus we feel the first effects in the upper part of the body—we get a headache. The fermentation produces warmth and we are soon conscious of the rise in the temperature of the blood. This is what we call fever. Fever can therefore only occur where foreign matter is present and the natural exits are stopped; that is (1) where there is no regular motion of the bowels; (2) where the urination is deficient; (3) where the pores are obstructed; (4) where the respiration is weak.
From this we get a very simple explanation of fever, which long years of observation and experience prove to be true.
by Louis Kuhne†
† Extracted from: Kuhne, Louis. 1899. The New Science of Healing. Leipzig: Kuhne.