CHAPTER XXXVI. 



PERCEPTION. 



IT is an axiom concerning which there is no dispute, The 

 that mind begins with sensation. It is also agreed by ^Jj^ 

 all, that sensation is inexplicable. But the most debated sensations 

 question of psychology is, how sensations give rise to to^pe"cep- 

 perceptions. ^^°^^- 



"When I speak of perception, I mean more than the Perception 

 mere cognition of a sensation. Any sensation whatever ^j^^n eoo-- 

 may be the object of cognition ; any sensation becomes the '"tion : 

 object of cognition in the act of directing attention to it. 

 But a sensation may be cognised without its giving rise 

 to any perception. Nothing, for instance, is perceived in 

 cognising the general sensation of being well or ill, vigorous 

 or weary. That which we perceive, according to what I 

 regard as the accurate use of the word, is not the sensation 

 itseK, but that to which we refer the sensation. And I it is the 

 propose to define perception, as that act hy %vhich the mind ^^ gg^g^? 

 refers sensations to their sources. I must, however, in some tions to 

 degree qualify this definition. The perceived source of a sources 

 sensation — that is to say, the source to which in the act of 

 perception we assign the sensation — may be remote in 

 space : thus, if I receive a ray of light from a star on my 

 eyes, and thereby perceive the star, that which I perceive 

 is at an almost immeasiirable distance. But the perceived 

 source of a sensation cannot be remote in time ; it must be 

 present in time ; if the source to which the mind refers 

 the sensation belongs to past time, the act of referring 

 the sensation to its source is not called perception, but 

 inference. Thus, if I cognise the sensation of thirst, I may 

 perceive that my throat is dry, and may infer that this is 



