SEJS-SATION. 3 



logical point of vieiv both sensations and perceptions differ from 

 * tliouglits ' (in the narrower sense of the word) in the fact that 

 nerve-currents coming in from the periphery are involved in their 

 production. In perception these nerve-currents arouse volumi- 

 nous associative or i^eproductive processes in the cortex; hut ivhen 

 sensation occurs alone, or imth a minimum of perception, the ac- 

 companying reproduxitive processes are at a minimum too, 



I shall in this chapter discuss some general questions 

 more especially relative to Sensation. In a later chapter 

 percejDtion will take its turn. I shall entirely pass by the 

 classification and natural history of our sj)ecial * sensa- 

 tions,' such matters finding their proper place, and being 

 sufficiently well treated, in all the physiological books.* 



THE COGNITIVE FITKrCTIOW OF SENSATION. 



A pure sensation is an abstraction ; and when we adults 

 talk of our ' sensations ' we mean one of two things : either 

 certain objects, namely simple qualities or attributes like 

 hard, hot, pain; or else those of our thoughts in which 

 acquaintance with these objects is least combined with 

 knowledge about the relations of them to other things. As 

 we can only think or talk about the relations of objects 

 wdtli w^hich we have acq^iaintance already, we are forced to 

 postulate a function in our thought whereby we first become 

 aware of the bai'c immediate natures by which our several 

 objects are distinguished. This function is sensation. 

 And just as logicians always point out the distinction 

 between substantive terms of discourse and relations found 

 to obtain between them, so psychologists, as a rule, are 

 ready to admit this function, of the vision of the terms or 

 matters meant, as something distinct from the knowledge 

 about them and of their relations i7iter se. Thought with 

 the former function is sensational, with the latter, intellec- 

 tuah Our earliest thoughts are almost exclusively sensa- 

 tional. They merely give us a set of thats, or its, of subjects 



* Those who wish a fuller treatment than Martin's Human Body affords 

 may be recommended to Bernstein's 'Five Senses of Man, 'in the Interna- 

 tional Scientific Series, or to Ladd's orWundt's Physiological Psychology. 

 The completest compendium is L. Hermann's Handbuch der Physiologic, 

 vol. ni. 



