Some men habitually find themselves fatigued, while others ordinarily end the day with a feeling of vigor. These contrary effects are not necessarily due primarily to disparity in the amount of energy spent or to unequal stores of energy available. The discrepancy in many instances is due to diverse attitudes toward the work or varying
degrees of success which has attended the work.
Pleasure secured in and from work is the best preventive and balm for tired muscles and jaded brains. Dislike or discomfort, on the other hand, adds to toil by sapping the strength of the worker.
Victory in intercollegiate athletic events depends on will power and physical endurance. This is particularly apparent in football. Frequently it is not the team with the greater muscular development or speed of foot that wins the victory, but the one with the more grit and perseverance. At the conclusion of a game players are often unable to walk from the field and need to be carried. Occasionally the winning team has actually worked the harder and received the more serious injuries. Regardless of this fact, it is usually true that the victorious team leaves the field less jaded than the conquered team. Furthermore the winners will report next day refreshed and ready for further training, while the losers may require several days to
overcome the shock and exhaustion of their defeat.
Recently I had a very hard contest at tennis. Some hours after the game I was still too tired to do effective work. I wondered why, until I remembered that I had been thoroughly beaten, and that, too, by an opponent whom I felt I outclassed. I had been in the habit of playing even harder contests and ordinarily with no discomfort--especially when successful in winning the match.
What I have found so apparent in physical exertion is equally true in intellectual labor. Writing or research work which progresses satisfactorily leaves me relatively fresh; unsuccessful efforts bring their aftermath of weariness.
_Intellectual work which is pleasant is stimulating and does not fag one, while intellectual work which is uninteresting or displeasing is depressing and exhausting_.
We can readily trace the source of energy in mechanical devices. The hands of a clock continue in their course because of the energy
locked up in a compressed spring or elevated weight. The gun projects the bullet because of the sudden chemical union of carbon with saltpeter and sulphur. The steam engine takes its energy from the steam secured by combustion of coal or other fuel.
The work of the human organism is usually classified as muscular or intellectual. In either the expenditure of energy is as dependent upon known causes as is the activity of the mechanical devices mentioned above.
Every muscular activity is dependent upon muscular cells ready for combustion; without such combustion no muscular work is performed.
Every intellectual process is likewise dependent upon brain cells ready for combustion, and no intellectual work can be performed without combustion of these brain cells.
To secure continued activity the clock must be rewound, the gun must be recharged, more coal must be supplied to the engine. In like manner the continuation of muscular and in-
tellectual activity depends upon the restoration of muscle and brain cells. The necessity for renewal is greater or less according to the amount stored in reserve and the rapidity of consumption. A maximum head of steam may keep the engine running for a long time unless the load is too heavy or the speed too great. Though under certain conditions the amount of muscle and brain energy stored in reserve is large, continuous or rapid activity of necessity expends the reserve and leads to exhaustion.
It is a simple process to rewind the clock, to reload the gun, and to replenish the fuel. To restore muscular and nerve cells is a very delicate process. So wonderful is the human organism, however, that the process is carried on perfectly without our consciousness or volition except under abnormal conditions.