PLAY 249 
imitation of what we have called the serious business of animal 
life, Professor Groos’s rejoinder is,* that “the conception of 
imitation here set forth—namely, as the repetition of serious 
activities to which the individual has himself become accus- 
tomed—cannot be applied directly to the primary phenomena 
of play—that is, to its first elementary manifestations” prior 
to any experience of these serious activities. The repetition 
(with a difference !) is in such cases not the re-enactment of 
what has been previously performed in full earnest by the 
individual, but rather the reappearance in the young of ances- 
tral modes of procedure—in other words, its specific character 
is such because it is a piece of instinctive behaviour or arises 
from instinctive proclivities. And this is the central point of 
the interpretation elaborated with great skill and candour by 
Professor Groos. Play is instinctive ; and its biological value 
lies in the training it affords for the subsequent earnest of 
life. 
Before leaving the surplus energy theory of play one more 
point made by Professor Groos may be mentioned. He con- 
tends that, though superabundant energy is a favouring con- 
dition of animal play (as it is, indeed, of all animal behaviour), 
still it is not a necessary condition. Animals often play when 
they are tired out. ‘“ Notice a kitten when a piece of paper 
blows past. Will not any observer confirm the statement that, 
just as an old cat must be tired to death or else already filled 
to satiety if it does not try to seize a mouse running near it, so 
will the kitten, too, spring after the moving object, even if it 
has been exercising for hours and its superfluous energies are 
entirely disposed of ? Or observe the play of young dogs. when 
two of them have raced about the garden until they are forced 
to stop from sheer fatigue, and they lie on the ground panting, 
with tongues hanging out. Now one of them gets up, glances 
at his companion, and the irresistible power of his innate 
longing for the fray seizes him again. He approaches the 
other, sniffs lazily about him, and, though he is evidently only 
half inclined to obey the powerful impulse, attempts to seize 
* Op. cit., p. 7. 
