The food need in summer is surprisingly small, so small that the average person will scarcely believe it. Some writers on dietetics advise eating as much in summer as in winter. How they can do so it is difficult to understand, for reason tells us that in summertime practically no food is needed for heating purposes, and that is how most of the food is used. A little experience and experiment show that reason is right. Nature herself confirms this fact, for at the tropics she has made it easy for man to subsist on fruits, while in the polar regions she furnishes him the most heating of all foods, fats. Because fats are so concentrated it is very easy to take too much of them. An ounce of butter contains as much nourishment as about twenty-five ounces of watermelon. Those who simplify their cooking and their combining and partake of food in moderation are repaid many times over in improved health. It is necessary to supply good building material in proper form if we would have health. CHAPTER XX. DRINK. There is but one real beverage and that is water. The other so-called beverages are foods, stimulants or sedatives. Milk is a rich food, one glass having as much food value as two eggs. Coffee, tea, chocolate and cocoa are stimulants, with sedative after-effects. Their food value depends largely on the amount of milk, cream and sugar put into them. Chocolate and cocoa are both drugs and foods. Alcohol is a stimulant at first, afterwards a sedative, and at all times an anesthetic. When we think of drinking for the sake of supplying the bodily need of fluid, we should think of water and nothing else. If other liquids are taken, they should be taken as foods or drugs. Water is the best solvent known. The alchemists of old spent much time and energy trying to find the universal solvent, believing that thereafter it would be easy to discover a method of making base metals noble. But they never found anything better than water. Water is the compound that in its various forms does most to change the earth upon which we live, and it is more necessary for the continuation of life than anything else except air. Pure water does not exist in nature, that is, we have never found a compound of the composition H2O. Water always contains other matter. The various salts are dissolved in it and it absorbs gases. The nearest we come to pure water is distilled. Pure water is an unsatisfied compound, and as soon as it is exposed it begins to absorb gases and take up salts and organic matter. Pure water differs from clean water. Clean or potable water is a compound which contains a moderate amount of salts, but very little of organic matter. Bacteria should be practically absent. Water that contains much of nitrogenous substances is unfit to use.