ORIGIN OF PHYSICAL CONCEPTS 19 



sensations only mark the interruptions in the 

 \ dynamic Activity in which we as potent beings 

 partake, and that they serve therefore to denote 

 and distinguish our Experience, but do not con- 

 stitute its essence. 



We do not propose now to devote any time to 

 the work of showing that sensations from their very 

 nature could never become the instruments of 

 Knowledge. We propose rather to turn to the 

 principal ideas of the external world which are 

 the common equipment of the Mind in order to 

 ascertain whether in point of fact they are derived 

 from Sensation. 



Of course to some extent the answer depends 

 on what we mean by Sensation. If by that term 

 we intend our whole Experience of the external, 

 then of course it necessarily follows or, at least, 

 we admit that our Knowledge of the external must 

 be thence derived. But such a use of the term is 

 loose, misleading, and infrequent. The only safe 

 course is to confine the term Sensation to the imme- 

 diate data of the five senses touch, sight, hearing, 

 smell, and taste, with probably the addition of 

 muscular and other internal feelings. It is in this 

 sense that the word is usually employed, and has 

 been employed by the Sensationalist School them- 

 selves. 



