716 THE PRINCIPLES OF SCIENCE. [CHAP. 



My own experience entirely bears out the opinion of De 

 Morgan, that classification according to the name of the 

 author is the only one practicable in a large library, and 

 this method has been admirably carried out in the great 

 catalogue of the British Museum. The name of the author 

 is the most precise circumstance concerning a book, which 

 usually dwells in the memory. It is a better characteristic 

 of the book than anything else. In an alphabetical 

 arrangement we have an exhaustive classification, in- 

 cluding a place for every name. The following remarks l 

 of De Morgan seem therefore to be entirely correct. 

 " From much, almost daily use, of catalogues for many 

 years, I am perfectly satisfied that a classed catalogue is 

 more difficult to use than to make. It is one man's theory 

 of the subdivision of knowledge, and the chances are 

 against its suiting any other man. Even if all doubtful 

 works were entered under several different heads, the 

 frontier of the dubious region would itself be a mere matter 

 of doubt. I never turn from a classed catalogue to an 

 alphabetical one without a feeling of relief and security. 

 With the latter I can always, by taking proper pains, make 

 a library yield its utmost ; with the former I can never 

 be satisfied that I have taken proper pains, until I have 

 made it, in fact, as many different catalogues as there are 

 different headings, with separate trouble for each. Those 

 to whom bibliographical research is familiar, know that 

 they have much more frequently to hunt an author than 

 a subject : they know also that in searching for a subject, 

 it is never safe to take another person's view, however 

 good, of the limits of that subject with reference to their 

 own particular purposes." 



It is often desirable, however, that a name catalogue 

 should be accompanied by a subordinate subject catalogue, 

 but in this case no attempt should be made to devise a 

 theoretically complete classification. Every principal 

 subject treated in a book should be entered separately in 

 an alphabetical list, under the name most likely to occur 



1 Philosophical Magazine, 3rd Series (1845), vol. xxvi. p. 522.* See 

 also De Morgan's evidence before the Royal Commission on the British 

 Museum in 1849, Report (1850), Questions, 5704* 5815*, 6481 

 6513. This evidence should be studied by every person who wishes 

 to understand the elements of Bibliography. 



