TERMINOLOGY AND NOMENCLATURE. 259 



ters may be changed, and another substituted as being better 

 suited for the purpose of distinction, while the word, still con- 

 tinuing to denote the same group of things, is not considered 

 to have changed its meaning. For this is no more than may 

 happen in the case of any other general name : we may, in 

 reforming its connotation, leave its denotation untouched ; 

 and it is generally desirable to do so. The connotation, 

 however, is not the less for this the real meaning, for we at 

 once apply the name wherever the characters set down in the 

 definition are found ; and that which exclusively guides us in 

 applying the term, must constitute its signification. If we 

 find, contrary to our previous belief, that the characters are 

 not peculiar to one species, we cease to use the term coexten- 

 sively with the characters ; but then it is because the other 

 portion of the connotation fails ; the condition that the class 

 must be a Kind. The connotation, therefore, is still the 

 meaning ; the set of descriptive characters is a true definition ; 

 and the meaning is unfolded, not indeed (as in other cases) by 

 the definition alone, but by the definition and the form of the 

 word taken together. 



6. We have now analysed what is. implied in the two 

 principal requisites of a philosophical language ; first, preci- 

 sion, or definiteness, and secondly, completeness. Any further 

 remarks on the mode of constructing a nomenclature must be 

 deferred until we treat of Classification ; the mode of naming 

 the Kinds of things being necessarily subordinate to the mode 

 of arranging those Kinds into larger classes. With respect to 

 the minor requisites of terminology, some of them are well 

 stated and illustrated in the "Aphorisms concerning the Lan- 

 guage of Science," included in Dr. Whe well's Philosophy of 

 the Inductive Sciences. These, as being of secondary impor- 

 tance in the peculiar point of view of Logic, I shall not further 

 refer to, but shall confine my observations to one more quality, 

 which, next to the two already treated of, appears to be the 

 most valuable which the language of science can possess. Of 

 this quality a general notion may be conveyed by the following 

 aphorism : 



17-2 



