The stomach, like every other organ of the body, is, for the wisest purposes, allowed a certain range, within which it may exercise its functions without injury to health; and it is only in virtue of such a power that it can adapt itself to the different circumstances in which an individual may be placed. If every trifling change in the quantity or quality of food were to be followed by mischievous consequences, no one could retain health for a single day; and if the stomach had no power of partially adapting itself to a particular kind of aliment, every change of place and of climate must soon have been attended by the loss of health and life; because there are scarcely any two places or countries in which precisely the same food would be set before us. According to this law of adaptation, which, of course, has its limits, the stomach may be accustomed to the reception of either a larger or a smaller quantity of food than what the necessities of the system require. If it is accustomed to too much, and less than usual be allowed, an unpleasant feeling of vacuity will arise, accompanied by a craving for more; but after a few days the unpleasant sensation will disappear, and the feeling of satisfaction be as great as if a full meal had been taken, and digestion will become more healthy and vigorous; whereas, if more food continues to be taken than what the system requires, merely to gratify the temporary craving, ultimate bad health will be the inevitable result. This is precisely the error which is generally fallen into. The stomach is accustomed during youth to receive and digest a larger quantity of food than what is requisite to carry on growth and repair the ordinary waste of the system; and from custom, _not from want_, we continue to fill it as liberally after growth is completed and waste is diminished, as we did before, when both were at their height. And if by any chance we eat less for a day or two, we mistake the temporary sense of emptiness for the indications of appetite, and are not satisfied till it is removed. The natural consequence is, that we educate the stomach to demand more food than the system requires, and more than it can itself continue to digest; and hence the numerous evils which we daily witness as fruits of indigestion.