In selecting and proportioning our food we should observe the laws of temperature or time of the year. We should not eat foods of a high caloric or heating value at a time when the sun is giving us this heat direct, thus building a fire inside, while the sun is giving us the same heat outside. The violation of this simple law is the cause of all sunstroke and heat prostrations. On the contrary, if we are going to be exposed to zero weather, we should build a fire inside by eating foods of a high caloric value. (3) As to work or activity: We should select and proportion our food according to the work we do, because eating is a process of making energy, while work is a process of expending energy, and we should make these two accounts balance. THE NORMAL DIET [Sidenote: Effects of overfeeding on starchy foods and sweets] While in some respects each body is a law unto itself, there are a few fundamental rules and laws that apply to all alike. For instance, overeating of starchy foods, in every case, will produce too much uric acid, and finally rheumatism. Also the overeating of sweets and starches will cause the stomach to secrete an over-supply of fermentative acids, the effects of which have been discussed in a previous lesson. [Sidenote: Temporary disturbances caused by radical changes in diet] In laying out the diet, under all conditions, the practitioner must be governed by the above-named rules. He should exercise his judgment, however, in each case according to the prevailing conditions. In prescribing diet it is well to remember that Nature will not tolerate, without protest, any radical change. It often occurs, therefore, that the most correct and thoroughly balanced menu will cause violent physical disturbances which the inexperienced may consider as unfavorable symptoms, but in a majority of cases this is merely the adjusting process, similar to that which occurs when the body is suddenly deprived of narcotics and stimulants after their habitual use. The practitioner should exercise much care in diagnosis. He should study all symptoms and lay out the diet so as to counteract prevailing conditions, and to produce normality. [Sidenote: The stomach should agree with natural food] The tendency of the body, that has been incorrectly fed for many years, to protest against the right kind and the right combinations of food, is often very deceptive. It is not always correct to say that the food did not agree with the stomach, but more correct to say that the different foods did not agree with themselves. The patient should be thoroughly acquainted with these facts, and mentally prepared for some temporary discomforts or physical protest against the new system. INFANT FEEDING [Sidenote: Large percentage of infant mortality due to incorrect feeding]