6 Chapter 1. 



importance from personal experience. On comparing 

 the first edition of his ''Lectures on Human and Animal 

 .Psychology," with the second edition, which we have 

 just quoted, it will not escape notice, that Wundt was 

 formerly influenced in his views on animal psychology 

 by the very ''pseudo-psychology" which he now so 

 justly condemns. Nevertheless, it can only redound 

 to his honor, that he had the courage to free himself 

 from the sway of that unscientific method; and we be- 

 lieve that other naturalists, who reason scientifically, 

 might follow his example, without the least injury to 

 their good name. 



Let us, then, begin our investigation with a critical 

 analysis of concepts. 



The key to a scientific inquiry into the nature of the 

 animal soul is evidently the soul of man. For we have 

 no immediate insight into the psychic acts of the animal ; 

 we can only infer their existence and nature from the 

 exterior actions which our senses perceive. We must 

 compare these manifestations of the activity of the 

 aiiimal soul with the manifestations of our own psychic 

 life, the interior causes of which are known to us from 

 our inner consciousness. Consequently scientific psy- 

 chology applies the same key as pseudo-psychology, but 

 it follows critical methods. It does not forget, as trie 

 other does, the fundamental law of a rational explana- 

 tion of nature which runs thus: We must explain 

 phenomena in the simplest way possible, and we are not 

 allowed to attribute to animals higher psychic facilities 

 than are requisite for the explanation of definite and 

 well-observed facts. 



This is the only correct standard. It is applied in 



