136 Animal Intelligence 
time than a dog with his whole life’s business. In the asso- 
ciations which are homologous with those of animals man 
outdoes them and adds an infinity of associations of a 
different sort. The primates would seem, by virtue of their 
incessant curiosity and addition to experience not for any 
practical purpose but merely for love of mental life, to 
represent an advanced stage toward this tremendous 
quantity of associations. In man not only this activity 
and curiosity, but also education, increases the number of 
associations. Associations are formed more quickly, and 
the absence of need for self-support during a long infancy 
gives time. Associations thus formed work back upon 
practical life, and by showing better ways decrease the 
need of work, and so again increase the chance to form 
associations. The result in the case of a human mind to- 
day is the possession of a thesaurus of valuable associations, 
if the time has been wisely spent. The free life of ideas, 
imitation, all the methods of communication, and the 
original accomplishments which we may include under the 
head of invention, make the process of acquisition in many 
cases quite a different one from the trial and error method 
of the animals, and in general much shorten it. 
Small as it is, however, fhe number of associations which 
an animal may acquire is probably much larger than popu- 
larly supposed. 
My cats and dogs did not mix up their acts with the 
wrong sense-impressions. The chicks that learned the 
series of twenty-three associations did not find it a task 
beyond their powers to retain them. Several three-day-old 
chicks, which I caused to learn ten simple associations in 
the same day, kept the things apart and on the next morning 
went through each act at the proper stimulus. In the hands 
of animal trainers some animals get a large number of 
