Every language under the sun contains a prayer somewhat similar to that which we have in the Anglo-Saxon tongue, “Give us this day our daily bread.” If we stop to think for a moment, we realize that next to the air we breathe, and the water we drink, our food is the most important consideration in the maintenance of life. All this is the veriest commonplace; yet the fact remains that it is very rarely indeed that we do stop to think upon the subject of our food. It is something that we take for granted, like life itself. In the regular routine of our days our meals become fixed habits, and the taking of food an almost involuntary custom. It requires some extraordinary event to arouse us to a just appreciation of the importance of knowledge on this subject. Or else the coming of one of the myriad forms of digestive diseases will serve the purpose of introducing the subject to our notice. Our blood is made directly from what we eat, and that old Saxon proverb is true which says that every man has lain in his own trencher. Man is his food. Each human body is made by chemical action from its food. All our actions and all our thoughts come from what we eat, even as the movements of machinery proceed from the coal fed into the boilers of the engine which operate the machine. If we eat the right food, namely, the food which contains the elements our bodies require in the proper proportions, we repair all waste, replace broken down tissue and supply ourselves with physical and mental energy for our toils and joys in life; while if we eat the wrong foods we quickly injure our delicate though powerful physical and mental machinery. All this would seem to be obvious; yet most people would grant that they have still much to learn concerning what really constitutes the best foods, and about the best ways of preparing, or making, or using those foods. Few of us possess anything more definite to guide us in our eating than the habits we acquired as children, or habits picked up in later life from following the example of our friends, or the food fashions of the day—for there are such things as fashions in foods and in the eating of foods, even as there are fashions in clothes and the making and wearing thereof. In this place it is proposed to study the subject of food from one standpoint, namely, its effect upon the Battle of the Blood; its relation to the vital resistance of the body whereby health is maintained. II HOW TO EAT: THE GOSPEL OF DIETETICS ACCORDING TO HORACE FLETCHER We shall first of all see what modern science has to tell us concerning the question of _how_ we ought to eat.