ON LIFE AND ORGANISATION. 309 



A similar course naturally suggests itself for the prosecution of 

 Comparative Psychology. 



Selecting animals with the simplest structure, and the least 

 complex external relations, and applying to the explanation of their 

 psychical manifestations the elementary facts and laws of Human 

 Psychology, we may reasonably expect indications of the nature of 

 such manifestations. 



As we are compelled, at the same time, by the nature of our 

 subject, to proceed from the knowledge of our own psychical con- 

 stitution, let us inquire what is the first stage in the evolution of 

 our own intelligence. 



It would appear to commence at birtb. It awakens contempo- 

 raneously with the arrival at its seat of certain of tbose so-called 

 impressions made upon the surface of the body of the infant by 

 the new medium into which it has entered. 



Some of these newly-arrived impressions are intended to co- 

 operate in the economy of the organism (reflex actions) ; but others 

 are immediately related to the awakened intelligence, and with 

 them only we have at present to do. They are the impressions on 

 the organs of the senses. 



Of these latter impressions the intelligence becomes aware. In 

 technical language, sensations are produced. The being experi- 

 ences sensations. 



To ascertain the nature of sensation, we must analyse its so- 

 called phenomena in our own consciousness, and combine the 

 results with what we know of the economy and actions of the 

 corresponding organs of the nervous system. 



Sensation may be defined to be apprehension, by the intelli- 

 gence of impressions transmitted to its seat from objects in the 

 surrounding medium, or in its own organism. 



This apprehension would appear to be immediate ; that is, the 

 apprehension is not a process ; for, as Sir William Hamilton has 

 pointed out, we cannot discriminate Sense from Intelligence. 



A process must be admitted, however, in the act of sensation. 

 It would appear to consist of three parts : — 



1. The impression on the organ of sense. 



2. The tnin mi ion of this impression along the nerve. 



:'». The recognition by the [ntelligence of what has been tran 



