Habits and cravings are certainly very unreliable indices of true physiological requirements. Man is constantly acquiring new habits, and these in time become second nature, forcing him to practise that which he has become accustomed to, regardless of whether it is beneficial or otherwise. The celebrated philosopher, John Locke, in his essay on education, says: "I do not think all people's appetites are alike • • • but this I think, that many are made gourmands and gluttons by custom, that were not so by nature; and I see in some countries, men as lusty and strong, that eat but two meals a day, as others that have set their stomachs by a constant usage, like Lamms, to call on them for four or five." Again, the so-called cravings of appetite are largely artificial and mainly the result of habit. A habit once acquired and persistently followed soon has us in its grasp, and then any deviation therefrom is very apt to disturb our physiological equilibrium. The system makes complaint, and we experience a craving, it may be, for that to which the body has become accustomed. There has thus come about a sentiment that the cravings of the appetite for food are to be fully satisfied, that this is merely obedience to nature's laws. In reality, there is no foundation for such a belief; any one with a little persistence can change his or her habits of life, change the whole order of cravings, thereby indicating that the latter are essentially artificial, and that they have no necessary connection with the welfare or needs of the body. The man who for some reason deems it advisable to adopt two meals a day in place of three or four, at first experiences a certain amount of discomfort, but eventually the new habit becomes a part of the daily routine, and the man's life moves forward as before, with perfect comfort and without a suggestion of craving, or a pang of hunger. Dietetic requirements, and standard dietaries, are not to be founded upon the so-called cravings of appetite and the instinctive demands for food, but upon reason and intelligence, reinforced by definite knowledge of the real necessities of the bodily machinery.

The standards which have been adopted more or less generally throughout the civilized world, based primarily on the assumption that man instinctively and independently selects a diet that is best adapted to his individual needs, are open to grave suspicion. The view that the average food consumption of large numbers of individuals and communities must represent the true nutritive requirements of the people is equally untenable. Naturally, there is general recognition of the principle that food requirements are necessarily modified by a variety of circumstances, such as age, sex, body-weight, bodily activity, etc. It is obvious that the man of 140 pounds body-weight needs less proteid than the man of 170 pounds, and that the man who does a large amount of physical work demands a larger calorific value in his daily diet, i. e., more carbohydrate and fat, than the sedentary individual. The growing child, in proportion to his body-weight, plainly needs more proteid for the upbuilding of tissue, and there are many conditions of disease where special dietetic treatment is undoubtedly called for. Our contention, however, and one which we believe to be perfectly justifiable, is that the true food requirements of the body, under any conditions, cannot be ascertained with any degree of accuracy by observations of what people are in the habit of eating; that customs and habits are not a safe index of true physiological needs. On the contrary, we are inclined to the belief that direct physiological experimentation, covering a sufficient length of time and with an adequate number of individuals, will prove far more efficient in affording a true estimate of the quality and quantity of food best adapted for the maintenance of good health, strength, and vigor.

Before considering these latter points, it is interesting to note, in passing, that during the last four centuries many thoughtful men have called attention to the apparent excessive use of food. There seems to have been in many quarters a more or less prevalent opinion that custom and habit were leading people on to methods of living, which were not in accord with the best interests of the community. It must be remembered, however, that arguments of this kind, even fifty years ago, could have been founded only on general observation and the application of common sense, since there were then no sound physiological data on which to predicate an opinion, or base a conclusion. Still, there were men of authority who attempted to lay before the people a proper conception of the temperate use of food. We have not the time here to consider many of these pleas, but I venture to call attention to the somewhat celebrated book published by the physician Thomas Cogan in 1596 under the title "The Haven of Health," and dedicated "to the right honorable and my verie good lord, Sir Edward Seymour, Knight and Earl of Hertford." Under the subject of diet, this old-time writer says: " The second thing that is to be considered of meates is the quantitie, which ought of all men greatly to be regarded, for therein lyeth no small occasion of health or sickness, of life or death. For as want of meate consumeth the very substance of our flesh, so doth excesse and surfet extinguish and suffocate naturall heat wherein life consisteth." Again, "Use a measure in eating, that thou maist live long: and if thou wilst be in health, then hold thine hands. But the greatest occasion why men passe the measure in eating, is varitie of meats at one meale. Which fault is most common among us in England farre above all other nations. For such is our custome by reason of plentie (as I think) that they which be of abilitie, are served with sundry sortes of meate at one meale. Yea the more we would welcome our friends the more dishes we prepare. And when we are well satisfied with one dish or two, then come other more delicate and pro-cureth us by that meanes, to eate more than nature doth require. Thus varietie bringeth us to excesse, and sometimes to Burfet also. But Phisicke teachetli us to faede moderately upon one kinde of meate only at one meale, or at leastwise not upon many of contrarie natures.... This disease, (I mean surfet) is verie common: for common is that saying and most true: That more die by surfet than by the sword. And as Georgius Pictorius saith, all surfet is ill, but of bread worst of all. And if nature be so strong in many, and they be not Bicke upon a full gorge, yet they are drowsie and heavie, and more desirouB to loyter than to labor, according to that old maeter, when the belly is full, the bones would be at rest. Yea the minde and wit is so oppressed and overwhelmed with excesse that it lyeth as it were drowned for a time, and unahle to use his force."