PREFACE 



make against the growing tendency to humanize 

 the lower animals. The paper was widely read and 

 discussed, and bore fruit in many ways, much of 

 it good and wholesome fruit, but a little of it bitter 

 and acrid. For obvious reasons that paper is not . 

 included in this collection. But I have given all the ^ 

 essays that were the outcome of the currents of 

 thought and inquiry that it set going in my mind, 

 and I have given them nearly in the order in which 

 they were written, so that the reader may see the 

 growth of my own mind and opinions in relation to 

 the subject. I confess I have not been fully able to 

 persuade myself that the lower animals ever show 

 anything more than a faint gleam of what we call 

 thought and reflection, the power to evolve ideas 

 from sense impressions, except feebly in the case 

 of the dog and the apes, and possibly the elephant. 

 Nearly all the animal behavior that the credulous 

 public looks upon as the outcome of reason is simply 

 the result of the adaptiveness and plasticity of 

 instinct. The animal has impulses and impressions 

 where we have ideas and concepts. Of our faculties 

 I concede to them perception, sense memory, and 

 association of memories, and little else. Without 

 these it would be impossible for their lives to go on. 

 I am aware that there is much repetition in this 

 volume, and that the names of several of the separate 

 chapters differ much more than do the subjects 

 discussed in them. 



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