GENERAL INTRODUCTION H ISTORIANS tell us already that this will be known as the age of public libraries as much as that earlier period when the world built its greatest churches is known as the age of cathedrals. The old library was a reservoir, getting in and keeping its books. The dominant note in the great work which in the past twenty-five years has revolutionized all ideas of librarianship has been to turn the reservir into a fountain, giving out freely and liberally in all directions. With the new century has come clearer conception of the fact that the third stage has begun, which, following the analogy of reservoir and fountain, might be called filtration. We have come to realize that mere reading is not necessarily good. It is the most powerful engine and most wonderful invention which the human mind has yet evolved. It is the longest lever with which human hands have ever pried; but this mighty engine is as powerful for evil as for good, and close students of the problem of tks and reading and libraries realize more and |