xxx.] CLASSIFICATION 715 



when we have forgotten all others ; but as we cannot usually 

 go to the expense of forming more than two or three 

 indices, we must select those circumstances which will 

 lead to the discovery of a book most frequently. Many 

 of the criteria mentioned are evidently inapplicable. 



The language in which a book is written is definite 

 enough, provided that the whole book is written in the 

 same language ; but it is obvious that language gives nr> 

 means for the subdivision and arrangement of the literature 

 of any one people. Classification by subjects would be an 

 exceedingly useful method if it were practicable, but ex- 

 perience shows it to be a logical absurdity. It is a very 

 difficult matter to classify the sciences, so complicated 

 are the relations between them. But with books the 

 complication is vastly greater, since the same book 

 may treat of different sciences, or it may discuss a 

 problem involving many branches of knowledge. A 

 good account of the steam-engine will be antiquarian, so 

 far as it traces out the earliest efforts at discovery ; purely 

 scientific, as regards the principles of thermodynamics in- 

 volved; technical, as regards the mechanical means of apply- 

 ing those principles ; economical, as regards the industrial 

 results of the invention ; biographical, as regards the lives 

 of the inventors. A history of Westminster Abbey might 

 belong either to the history of architecture, the history of 

 the Church, or the history of England. If we abandon the 

 attempt to carry out an arrangement according to the 

 natural classification of the sciences, and form comprehen- 

 sive practical groups, we shall be continually perplexed by 

 the occurrence of intermediate cases, and opinions will 

 differ ad inftnitum as to the details. If, to avoid the dif- 

 ficulty about Westminster Abbey, we form a class of books 

 devoted to the History of Buildings, the question will then 

 arise whether Stonehenge is a building, and if so, whether 

 cromlechs, mounds, and monoliths are so. We shall be 

 uncertain whether to include lighthouses, monuments, 

 bridges, &c. In regard to literary works, rigorous classifi- 

 catiqn is still less possible. The same work may partake 

 of the nature of poetry, biography, history, philosophy, or 

 if we form a comprehensive class of Belles-lettres, nobody 

 can say exactly what does or does not come under the 

 term. 



