59§ THE POPULAR SCIENCE MONTHLY 



persistent striving of the organism toward an end, that end being 

 usually some changed relation which shall subserve the life purposes of 

 the individual. This striving has for its subjective correlate a state 

 which we may characterize as tension, strain, stress or effort. It is this 

 aspect of human behavior that constitutes work and distinguishes it 

 from play. It is the power to hold oneself to a given task for the sake 

 of a given end, to carry on an occupation even though it may have 

 ceased to be interesting for the sake of some end to be gained other than 

 the activity itself. This is work and it involves stress, strain, tension, 

 effort, endeavor, concentration, application and inhibition, and is un- 

 conditionally the ground of progress. It is precisely the lack of this 

 capacity for sustained and persevering effort that characterizes all un- 

 civilized races. 



Play is just the opposite and includes all activities in which the 

 stress and strain are absent. Play is self-developing and supplies its 

 own incentive. It is spontaneous and pleasant because of the sense of 

 ease which accompanies it. Clearly play in this sense is something 

 broader and more inclusive than those activities which we usually em- 

 brace under the term. It includes not merely children's plays and 

 grown-ups' sports, not only hunting, fishing, boating, yachting, motor- 

 ing, flying and all kinds of outing, not merely games and races and 

 spectacles and tournaments and fairs and expositions, but also the 

 theater and the opera, the enjoyment of music and painting and poetry, 

 our daily paper and our magazines and our novels and our romances, 

 and for that matter, many forms of so-called work in which the inter- 

 est is self-developing, such, for instance, as gardening for pleasure. Ee- 

 laxation or recreation would be perhaps more fitting terms to designate 

 this large class of human activities. 



All the evidence that we have points to the validity of the law that 

 those peculiar forms of mental activity which have developed late in the 

 evolution of man are most affected by fatigue — a law fully sustained by 

 the study of psychasthenics and their incapacity for higher mental 

 operations, as well as by the observation of people normally fatigued, 

 while it is known that the disintegration of the nervous system in dis- 

 ease follows the reverse order of its development. 



The application to the explanation of adult sport is evident. Those 

 forms of mental activity which are developed late in the history of the 

 race, and late in the life of the child, that tense and strenuous activity 

 upon which modern progress depends, the power to hold ourselves by 

 sustained attention and sustained effort down to hard and uninterest- 

 ing tasks for the sake of some ultimate end, the concentration of the 

 mental forces upon problems of science, philosophy and inven- 

 tion, and the inhibition of old and undesirable responses — all these 

 bring quick and extreme fatigue and demand rest for the corresponding 



