CHAPTER XII 
THE INTELLIGENCE OF MAMMALS 
“Le premiére partie de cet ouvrage démontre que les bétes sont 
capable de quelques connoissances. Ce sentiment est celui du 
vulgaire: il n’est combattu que par des philosophes, c’est 4 dire, 
par des hommes qui d’ordinaire aiment mieux une absurdité qu’ils 
imaginent, qu’une vérité qui tout le monde adopt.’’—ConpiLLac, 
Traité des Animauz. 
“The power of association over brutes is very evident in all the 
tricks which they are taught; and the whole nature of each brute, 
which has been brought up among others of the same species, is a 
compound of instinct, his own observations and experiences, and 
imitation of those of his own species.””—HarTLeEy, Observations on 
Man. 
“Animals pass from one imagination to another by the connection 
which they have felt before; for example, when his master takes a 
stick, the dog fears a whipping. And in many instances children 
with the rest of mankind proceed nowise differently in their passages 
from thought to thought.’”—Lerrsnitz, New Essays Concerning 
Human Understanding. 
Until quite recently most of our knowledge of the psy- 
chology of mammals, as of other animals, was obtained 
simply by watching them. In this way has been accumu- 
lated a large fund of information concerning their instincts 
and habits, and to a certain extent their general intelligence. 
But in this as in other fields of investigation, the method of 
experiment has come to be indispensable when the attempt 
is made to study the phenomena analytically. There is of 
course no especial magic in the experimental method; it is 
simply a means of improving the conditions of observation. 
And in animal psychology especially, the method may have 
drawbacks which counterbalance some of its advantages. 
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