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 <p 170> 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 <p 171> 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.