It is a useful axiom for the cataloguer that he must ascertain clearly what is the definite subject of a book before he decides upon the proper subject-heading for it in the dictionary catalogue, as he is compelled to do before he can assign the exact place for a book in the classified catalogue. Further, he should not attach too much importance to the terms of the title-page in the process, else he will stumble on "pitfalls" in the shape of titles that may mislead, and so be induced to place a book on artificial lighting with the title "The art of illumination" under the wrong kind of "Illuminating," an "Essay on Irish bulls" under "Cattle," "The psychology of socialism" under "Mind," and "The Fine Art of Jujutsu" under "Art," even misread "Jujutsu" as the name of an artist.
As already stated, it is well to avoid scattering books upon a single subject, even if viewed from varying standpoints, under several headings throughout the catalogue, if they can be reasonably brought together, and the fact that the books are in different languages must not be allowed to affect the matter. As a case in point, we may take such a subject of the day as "Tariff Reform." It is both possible and desirable to concentrate under some appropriate and inclusive heading, say "Free Trade Question" or "Tariffs," the books for and against free trade; embodying under it those dealing with special aspects of the question, instead of scattering them, on account of the terms used on their title-pages, under "Protection," "Food Taxes," "Imperial Preference," "Tariffs," "Fiscal Question," "Tariff Reform," "Fair Trade," "Reciprocity," etc. When these terms occur in the titles, a reference from them to the heading can easily be given if thought desirable. Omitting the principal entries, this may be illustrated by showing several books of apparently very different views that really bear upon this question, and justify inclusion under it.
=Free Trade Question=: Ashley, P. Modern tariff history. 1904 Aubry, P. Etude critique de la politique commerciale de l'Angleterre. 1904 Avebury, Lord. Free trade. 1904 Taussig, F. W. The tariff history of the United States. 1901 Unwin, Mrs. C. (_Ed._) The hungry forties. 1904 Williams, E. E. The case for protection. 1899 -- "Made in Germany." 1896 Williamson, A. British industries and foreign competition. 1894