REQUISITES OF LANGUAGE. 247 



parties of living bodies; it might escape altogether 

 the notice of an unscientific observer. Yet great 

 authorities (independently of M. de Blainville, who is 

 himself a first-rate authority,) have thought, seemingly 

 with much reason, that no other property so well 

 answers the conditions required for the definition. 



5. Having laid down the principles which ought 

 for the most part to be observed in attempting to give 

 a precise connotation to a term in use, I must now 

 add, that it is not always practicable to adhere to those 

 principles, and that even when practicable, it is occa- 

 sionally not desirable. Cases in which it is impossible 

 to comply with all the conditions of a precise defini- 

 tion of a name in agreement with usage, occur very 

 frequently. There is often no one connotation capable 

 of being given to a word, so that it shall still denote 

 everything it is accustomed to denote; or that all the 

 propositions into which it is accustomed to enter, and 

 which have any foundation in truth, shall remain true. 

 Independently of accidental ambiguities, in which the 

 different meanings have no connexion with one ano- 

 ther; it continually happens that a word is used in 

 two or more senses derived from each other, but yet 

 radically distinct. So long as a term is vague, that 

 is, so long as its connotation is not ascertained and 

 permanently fixed, it is constantly liable to be applied 

 by extension from one thing to another, until it reaches 

 things which have little, or even no, resemblance to 

 those which were first designated by it. 



Suppose, says Dugald Stewart, in his Philosophical 

 Essays*, " that the letters A, B, C, D, E, denote a series 

 of objects; that A possesses some one quality in com- 



P. 217, 4to edition. 



