Libraries, like the books they house and distribute, have multiplex reasons for their existence. Their highest aim, like that of education itself, is to promote the mental and spiritual life of the community; they are humanist foundations. But the race must be conserved; our daily needs must be satisfied. National safety, liberty to develop ourselves, the economy of our physical existence, must be assured, or humanism is a chimera. Our libraries must perform their necessary part in the functions we label utilitarian, without, however, omitting or slackening in their higher purposes. A general library, in short, is concerned not only with human knowledge, but also with every human interest and activity; not only with science, philosophy, theory, but with all the practical arts, those which are for the preservation, as well as those which are for the highest development of humanity. In the department of the public library now to be considered these material objects are the main concern. A modern commercial library is something utterly different from any library heretofore considered. Here, as an advocate of more and better commercial and technical libraries puts it, “The humanist will have to give way to the economist and man of science.” [Illustration: PATENT OFFICE LIBRARY.] From their earliest years, public libraries have admitted these claims, and they have put forth special efforts to supply the peculiar needs of the working classes. The nature of the industries carried on has been the chief factor determining the directions in which the stock of books should differ in any given locality from what may be described as the standard selection. Text-books on such industries and their subsidiary subjects, illustrated treatises and other expensive works of reference, have been provided as liberally as funds permitted; and the same attention has been paid to the local trades and professions. Certain obvious restrictions must be allowed for, besides limited resources. Few places have been able to provide a law library or an extensive collection of medical books. The solicitor usually has his own book-case of legal literature, and so with the physician and surgeon; they also have access to large professional libraries. Nevertheless, if the public library seems to disregard certain professions, it is rather on the score of expense and of limited demands than that it disclaims its duty. A national system of libraries would certainly have to provide for these classes, probably by organizing a central supply and loans to the nearest library, in the way proposed for dealing with the more advanced and costly technical works for industries.