In considering the chemical harmony of foods, the student should keep in mind the time required for digestion, which involves not only the question of combining foods at the same meal, but also the taking, within a few hours after eating, of other articles that may produce chemical inharmony. For example: Milk, cereals, and sweet fruits are in chemical harmony, but a lemonade introduced into the stomach an hour or two later would produce inharmony, and be almost as harmful as if it had been taken with the meal. [Sidenote: Instinct a safe guide, if cultivated] There are many injurious combinations which the student will learn to omit from a sense of taste and instinct, and while our instincts have in many cases ceased to guide us aright, they will rapidly return and assume command if given a fair opportunity. The perfect meal can be made from three or four articles, and the entire menu can be changed three times a day, but to take eight, ten, or a dozen things at the same meal, puts the quantity, as well as every article composing the meal, into jeopardy. After one has eaten a sufficient quantity of food, and the taste has signalled "ENOUGH," something sweet or pungent is introduced. This puts into activity another set of taste buds which will accept a given quantity of another food. However, the stomach has already given off one signal of "enough," hence every pennyweight taken in excess of that amount is that much more than should be eaten. In order to simplify the making of harmonious combinations, I have grouped the foods whose use I recommend in nine different divisions. A further subdivision of vegetables and fruits might have been made, but this would have increased the number of groups, making them more complicated and less practical. HOW TO INTERPRET THE TABLES In order to ascertain the articles with which any special food will combine, the student should turn to the table headed with the desired article of that group. If foods from three groups are to be considered, the student will look for two of them in the first vertical column on the left-hand side of the page, and will then follow across to the vertical column for the third article. Figure (1) means especially beneficial Figure (2) means good combinations Figure (3) means somewhat undesirable Figure (4) means particularly harmful (a) "Fats with" figure (1), under the heading _Grains_, first table, page 609, means that the combination of "fats with grains" would be "especially beneficial." (b) "Fats and eggs with" figure (2), under the heading _Milk_, page 609, means that "fats and eggs with milk" make a good combination. (c) "Fats and milk with" figure (3), page 609, under column headed _Nuts_, means a "somewhat undesirable" combination. (d) "Fats and acid fruits with" figure (4), under heading _Milk_, page 609, means that this combination would be "particularly harmful," etc.