There are others who can carry the regular amount but not more without injury to their health.
College grades afford a means of recording intellectual efficiency directed toward particular problems. With no apparent change in bodily conditions the same student frequently increases his efficiency a hundred per cent. The increase seldom has an injurious effect on health, but is merely evidence of the fact that he has suddenly wakened up and is applying energies which before were undiscovered. A slow walk for a single mile leaves many persons ``dragged out'' and exhausted, but a brisk walk of the same or a greater distance results in invigoration and recuperation. Likewise the droning over an intellectual task results in exhaustion, while vigorous treatment whets the appetite for additional problems.
This swift, decisive attack on problems was
the method of Edward H. Harriman, who crowded into ten years the railroad achievements of an extraordinary lifetime. Decisions involving expenditure of many millions of dollars were arrived at so quickly as to seem off-hand, even reckless. In reality, they were the products of brief periods of intense application in which he reviewed all the conditions and elements involved, and forged his conclusion, as it were, at white heat. Back of each decision was exact and thorough knowledge of the physical and traffic conditions of each of his railroads. In the case of the Union Pacific, at least, he gained this mastery by patient, intensive study of each grade and curve and freight-producing town on its 1800 miles of track.
The inhabitant of the torrid zone upon moving to a northern climate is severely affected by the chill of the atmosphere. The discomfort may last for days or months, but he becomes acclimated and is able to withstand the cold without serious discomfort. Likewise the inhabitant of a cool climate feels exhausted
by the heat of the torrid zone. In some cases he is unable to accustom himself to the change, but in many instances the acclimatization follows rapidly and leaves the individual well fortified against the dangers of excessive heat.
Persons who have accustomed themselves to stimulants of any sort are completely depleted if they are unable to get the special form to which they have been accustomed. This holds true for tobacco, morphine, coffee, and many other forms of stimulants actually indulged in by many persons. If they are able to resist the temptation and deny themselves the stimulant, the period of exhaustion soon disappears and the subject may even lose all craving for that which formerly seemed essential to his very existence.
The quantity which we eat is partly a matter of habit. There is doubtless a minimum of nourishment which is absolutely necessary for health and strength. On the other hand there is doubtless a maximum limit which cannot be passed without serious injury. Our bodies seem to demand the amount of
food to which we have accustomed them. If we should increase the amount ten or twenty per cent, we might, for a while, feel some discomfort from it, but soon our system would begin to demand the greater quantity and we could not again return to the lighter diet without a period of discomfort. Likewise the amount of food which most of us consume could be reduced materially with no permanent injury or reduction of energy or danger to health. Following the reduction would be a period of discomfort and probable reduction of weight. This period would last for but a relatively short time, after which we would again strike a physiological equilibrium such that an increase of food would not be craved nor be of any benefit.
Any great increase in the amount of physical or mental work results in a feeling of weariness which is usually sufficient to cause us to return to our habitual amount of expenditure of energy. Our system is, however, wonderful in its capacity to adjust itself to changed demands which come upon it, whether these
demands be in the nature of changes in temperature, in stimulants, in nourishment, or in the expenditure of physical or mental energy.