Many causes have been assigned for goitre, but no one knows for certain which is the correct one. Because of its prevalence in Switzerland and in other mountainous regions, where the inhabitants are obliged to depend upon water which was originally snow for their drinking supply, it was thought that the condition arose as a result of the lack of lime and other mineral salts ordinarily found in water which had been more intimately in contact with the earth. Yet the feeding of these mineral salts to those afflicted with goitre made no appreciable difference in the condition of these patients. Other observers have ascribed goitre to the influence of the nervous tension, under which we live in this era of break-your-neck-to-get-there-and-do-it. Others locate the seat of this disease in the brain itself, in the blood vessels, and in the blood; others, who favor the so-called “mechanical theory,” ascribe the symptoms to compression by an enlarged thyroid gland of the nerves and vessels in the neck, although they neglect to tell us how the gland became enlarged, in the first place. Many authorities claim that the trouble originates most frequently as a result of eye strain. They insist that the visual centres, using as they do, one-third of all the brain energy, are overworked, in our intensive modern life, and react upon the body to produce the toxins of fatigue. The thyroid body, one of whose functions it is to secrete a product which tends to neutralize these toxins, works overtime on the job, and not knowing when to quit, keeps right on working--with the result that the system is overcharged with thyroid extract. This thyroidism, as it is called, ultimately produces the goitrous symptoms. Other clinicians contend that the disease is of microbic origin--which is quite unlikely--because when the glands have been brought to the autopsy table and the pathological laboratory, microbes have not been found in quantity sufficient to cause these grave symptoms. But what interests and discourages those afflicted most is that if the cause is known, the successful treatment is even more unknown. Medical men have treated these conditions on the general supposition that there was either too much or not enough thyroid extract secreted and discharged into the circulation by the thyroid gland. So they gave thyroid tablets, made from the dried and pulverized glands of sheep. If these diminished the intensity of the symptoms, the doctors knew that the gland was deficient in its functioning powers, and that furnishing an additional supply from the glands of our woolly brothers would tend to restore the thyroid deficiency in us.