Any discussion of the digestibility of foods must be general, because food which agrees with one may disagree with another, and a food which disagrees with one at a particular time may entirely agree with him at some other time according to the condition of his system. Therefore, before one passes on the adaptability of a food to his system, he should know that this food agrees or disagrees with him under various conditions. The chances are that the food is right but that the attitude of mind and the condition of the body are abnormal. The digestibility of food depends largely on the physical condition of the individual, because the amount of digestive juices poured into the alimentary canal is influenced by this condition, particularly by the condition of the nerves. If sufficient juices, in proper proportions, are not poured into the digestive tract, the foodstuffs are not made soluble for absorption. Digestion is practically synonymous with solution—all solid foods must be reduced to a liquid state by means of the digestive juices and water before they can pass through the walls of the stomach and intestines and enter the blood. Each individual should learn to like the foods containing the nutrient elements which experience and blood tests have shown to be lacking in his case. Yet while it is true that in most cases the aversion to a particular food is largely mental, there are kinds of food which, to certain individuals, according to the chemical composition of the body, act as actual poisons, _e. g._, strawberries, cheese, or coffee. The question of likes and of dislikes in foods, is largely habit, and one can learn to like almost any food, if one really has the desire to do so. When the habit has been formed of discriminating too much in the food, of discarding this food or that, because at some time it has disagreed, due to the particular condition at the time, the mind approaches the table in a pessimistic attitude and the saliva and the gastric juices are retarded in their flow. When one is exercising freely, so that the muscular and mucous coats of the digestive system are strong, the body will handle foods which, during sedentary habits, it would not digest. _Much indigestion is due to mental apathy. The mind often needs arousing to an interest in something._ Such an individual needs to know that one of the hardest things for the members of his family is to live day by day with one who maintains an attitude of mental depression, and he should stir himself for “his stomach’s sake,” as well as for the sake of his family, to a cheerful interest in something. He should let go his grudge and ride a hobby, if it is a cheerful one, and ride it hard. It may be well, here, to trace, briefly, the progress of the food through the digestive tract and the action of the juices and the ferments on it.[5] * * * * * [Sidenote: Salivary Digestion]