76 GENERAL VIEW AND BASIS OF SCIENTIFIC RESEARCH. 



represent but a single idea or thing, and have but a single 

 meaning ; but language jis extremely incomplete and im- 

 perfect. Sometimes we have no name at all for a thing, 

 and sometimes only one for a very great number. Thus 

 we have no single word which means 'undiscovered truth,' 

 whilst the name John Smith has several thousand mean- 

 ings. Some thoughts are unutterable in words, and lan- 

 guage entirely fails to convey their meaning ; in other 

 cases, many ideas have but few representatives in lan- 

 guage ; thus, for all the multitudes of ideas of shades of 

 colour, of different flavours, odours, sounds, and feelings 

 of pain or pleasure, we possess only a comparatively few 

 representative terms. Similar things also should be called 

 by similar names, and dissimilar ones by dissimilar names ; 

 but in this country and in Germany, in the case of the 

 magnetic polarities of the earth and of a magnet, similar 

 things are called by dissimilar names, and dissimilar ones 

 by similar names. Thus, whilst we call that part of the 

 Earth which possesses north polarity the north pole, that 

 end of the magnet which possesses the same property we 

 call the south pole. In no subject perhaps are the mean- 

 ings of words more vague than in that of mental science, 

 and this arises chiefly in consequence of our retention of 

 ill-founded metaphysical ideas, and our great ignorance of 

 the operations of the brain and mind. When a term 

 represents several different ideas, and has several different 

 meanings, it is rendered ambiguous and equivocal, unless 

 the particular idea or meaning is stated at the time. We 

 should, therefore, endeavour not to attach more than one 

 meaning to each term in a single discourse, otherwise we 

 commit a fallacy. Ambiguous terms are dangerous instru- 

 ments, and some of them are exceedingly subtle and difficult 

 to render clear. In consequence of the more definite nature 

 of ideas in the simple sciences, the more demonstrable 



