(2) _Popularity._ Merely to place books on the shelves of a Sunday-school library will not insure the reading of them. This library aims to be emphatically a circulating library. Its books are not for show, but for use; and their place to be seen is not on the shelves of the library-room, but in the homes of the scholars and teachers. It is absolutely essential that no book be placed in the library unless it is sufficiently interesting to be taken out and read, for an unread book is worse than useless in the Sunday-school library. Although its principles be as sound as the Ten Commandments, if it be dull it must be condemned. Students may be willing to plod through an uninteresting book because it is profitable, but ordinary readers, especially youthful readers, will turn from it. Books should not be purchased because they are good, or because they are cheap; nor, on the other hand, should they be chosen only because they are popular; yet an interesting, popular quality should be an absolute requirement in every book placed upon the library shelves. (3) _Literary Quality._ Books are influential teachers, and a style like that of Hawthorne or Eliot will unconsciously mold the language of those who read it. On the other hand, the habitual readers of the slang in the comic paragraph of the newspaper will talk in a careless and inelegant manner. Of course, all books should be excluded from the library which deal in low, profane, or immoral language, without regarding the specious plea that such describe life as it is. We do not need to learn the language of the slums to know life; and, as one writer has said, we do not want a realism that can be touched only with a pair of tongs. The best pirate story in the English language is one that is without an oath from cover to cover,[10] and we would not exclude it from the Sunday-school library. Let us seek for writers whose expression is direct, smooth, and cultured. The Sunday school in its literature as well as its teaching should lead upward toward refinement of taste.