488 OPERATIONS SUBSIDIARY TO INDUCTION. 



ing. Combinations of sensations or feelings may always be described, if 

 we have a name for each of the elementary feelings which compose them ; 

 but brevity of description, and clearness (which often depends very much 

 on brevity), are greatly promoted by giving distinctive names not to the 

 elements alone, but also to all combinations which are of frequent recur- 

 rence. On this occasion I can not do better than quote from Dr. Whe- 

 well* some of the excellent remarks which he has made on this important 

 branch of our subject. 



" The meaning of [descriptive] technical terms can be fixed in the first 

 instance only by convention, and can be made intelligible only by present- 

 ing to the senses that which the terms are to signify. The knowledge of 

 a color by its name can only be taught through the eye. No description 

 can convey to a hearer what we mean by apple-green or French gray. 

 It might, perhaps, be supposed that, in the first example, the term apple, 

 referring to so familiar an object, sufficiently suggests the color intended. 

 But it may easily be seen that this is not true ; for apples are of many dif- 

 ferent hues of green, and it is only by a conventional selection that we can 

 appropriate the term to one special shade. When this appropriation is 

 once made, the term refers to the sensation, and not to the parts of the 

 term ; for these enter into the compound merely as a help to the memory, 

 whether the suggestion be a natural connection as in ' apple-green,' or a 

 casual one as in 'French gray.' In order to derive due advantage from 

 technical terms of the kind, they must be associated immediately with the 

 perception to which they belong ; and not connected with it through the 

 vague usages of common language. The memory must retain the sensa- 

 tion; and the technical word must be understood as directly as the most, 

 familiar word, and more distinctly. When we find such terms as tin-iohite 

 or pinchhecTc-hrown, the metallic color so denoted ought to start up in our 

 memory without delay or search. 



"This, which it is most important to recollect with respect to the sim- 

 pler properties of bodies, as color and form, is no less true with respect to 

 more compound notions. In all cases the term is fixed to a peculiar mean- 

 ing by convention ; and the student, in order to use the word, must be com- 

 pletely familiar with the convention, so that he has no need to frame con- 

 jectures from the word itself. Such conjectures would always be insecure, 

 and often erroneous. Thus the term papilionaceous applied to a flower is 

 employed to indicate, not only a resemblance to a butterfly, but a resem- 

 blance arising from five petals of a certain peculiar shape and arrangement ; 

 and even if the resemblance were much stronger than it is in such cases, 

 yet, if it were produced in a different way, as, for example, by one petal, or 

 two only, instead of a ' standard,' two 'wings,' and a 'keel' consisting of 

 two parts moi'e or less united into one, we should be no longer justified in 

 speaking of it as a ' papilionaceous ' flower." 



When, however, the thing named is, as in this last case, a combination 

 of simple sensations, it is not necessary, in order to learn the meaning of 

 the word, that the student should refer back to the sensations themselves; 

 it may be communicated to him through the medium of other words ; the 

 terms, in short, may be defined. But the names of elementary sensations, 

 or elementary feelings of any sort, can not be defined ; nor is there any 

 mode of making their signification known but by making the learner ex- 

 perience the sensation, or referring him, through some known mark, to his 



* History of Scientific Ideas, ii., 110, 111. 



