308 ON LIFE AND ORGANISATION. 



We may therefore reasonably expect, by the careful investiga- 

 tion of the habits and actions of animals, aided by cautious general- 

 isation, to derive much important psychological knowledge. Such 

 knowledge will ultimately assume the form of a sub-science — 

 Comparative Psychology. 



The facts of Human Psychology are attained directly through 

 the consciousness ; but the generalisations of Comparative Psycho- 

 logy must necessarily continue to be indirect. 



We must, therefore, compare the facts and laws of the Psychology 

 of man, with the indications or manifestations of apparently similar 

 facts and laws in the brute. 



It will at once be admitted, that the central fact of our psychi- 

 cal constitution is the existence of a power within us, in virtue of 

 Avhich we possess the faculties of Knowing, Feeling, and Willing. 



To this power we may apply the term Intelligence — employing 

 the word in the broad sense of which it is susceptible. 



That a corresponding power exists in the brute will, I believe, 

 be generally admitted. 



There appears, however, to be a very marked difference between this 

 power as it exists in man, and even the highest form of it in the brute. 



In man it is fully evolved, capable of being scrutinised as an 

 object by its possessor. 



In the brute it is semi-evolved, and, as we shall in the sequel 

 find grounds for concluding, unconscious of itself. 



It would appear to exist in the simplest forms in the simplest 

 animals. As we extend our observations up the animal series, it 

 appears, as recognised by its manifestations, in forms more and 

 more complicated, in species above species, but never reaching, 

 even in the Orang, the stage of self-consciousness. 



Intelligence always manifests itself in connection with certain 

 organs and parts of the animal. 



It is not, however, produced by, or secreted from, these parts or 

 organs, but only, as has been already stated, evolved parallel to, 

 and in harmony with, their development. 



In the study of Comparative Anatomy, much success has been 

 attained by commencing with the examination of the simplest 

 forms, and extending our observations upwards, in a series of in- 

 creasing complexity. 



