THE PLAY OF ANIMALS. 



CHAPTEE I. 



THE SURPLUS ENERGY THEORY OF PLAY. 



The most influential theory of play explains it by 

 means of the surplus energy principle. In what follows 

 I shall attempt to demonstrate that this theory has not 

 the scope usually attributed to it. It owes its develop- 

 ment and extension principally to Herbert Spencer, but 

 it is based on a principle of Schiller's, in whose philoso- 

 phy, however, it holds but a subordinate place. It is 

 necessary here in the beginning of the inquiry, to set 

 Schiller's priority in the right light, as it does not seem 

 to be generally known. Schiller's treatment of play 

 and the play instinct is to be found in his excellent let- 

 ters On the ^Esthetic Education of Mankind. Later I 

 shall enter more fully into their contents, confining 

 myself here to the passage on which the theory of sur- 

 plus energy is especially based. It is in the twenty- 

 seventh letter, and reads as follows: " Nature has indeed 

 granted, even to the creature devoid of reason, more 

 than the mere necessities of existence, and into the 

 darkness of animal life has allowed a gleam of freedom 

 to penetrate here and there. When hunger no longer 

 torments the lion, and no beast of prey appears for him 

 to fight, then his unemployed powers find another out- 

 let. He fills the wilderness with his wild roars, and his 

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