CHAPTER XI. 



CLASSIFICATION. 



98. THAT orderly arrangement of objects called Classi- 

 fication has two purposes, which, though not absolutely 

 distinct, are distinct in great part. It may be employed to 

 facilitate identification, or it may be employed to organize 

 our knowledge. If a librarian places his books in the alpha- 

 betical succession of the author's names, he places them in 

 such way that any particular book may easily be found, but 

 not in such way that books of a given nature stand together. 

 When, otherwise, he makes a distribution of books according 

 to their subjects, he neglects various superficial similarities 

 and distinctions, and groups them according to certain pri- 

 mary and secondary and tertiary attributes, which severally 

 imply many other attributes groups them so that any one 

 volume being inspected, the general characters of all the 

 neighbouring volumes may be inferred. He puts together 

 in one great division all works on History; in another all 

 Biographical works; in another all works that treat of 

 Science ; in another Voyages and Travels ; and so on. Each 

 of his great groups he separates into sub-groups; as when 

 he puts different kinds of Literature under the heads of 

 Fiction, Poetry, and the Drama. In some cases he makes 

 sub-sub-groups; as when, having divided his Scientific trea- 

 tises into abstract and concrete, putting in the one Logic 

 and Mathematics and in the other Physics, Astronomy, 

 Geology, Chemistry, Physiology, &c. ; he goes on to sub-divide 

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