So many and varied are the paths of musical enjoyment and profit opened out in the following pages, so different and sometimes so conflicting are the types of art represented there, that the timid or inexperienced reader may well pause at the threshold, afraid of wholly losing his way in such a labyrinth. He may hesitate to trust himself in so unfamiliar a landscape without first seeing some sort of small-scale plan of the ground, which, omitting the confusing details, shows in bold relief only the larger and essential divisions--the 'lay of the land.’ Such a plan it is the object of this introduction to furnish. Of the two most general types of reader, the professional musician and the amateur or lover of music, the first is least in need of such assistance. His keen interest in his specialty will naturally determine the order of his reading; he will look first for all he can find about that, and later work out from that centre in various directions, and meanwhile the plan peculiar to this work of assembling all information on a given subject contained in any of the volumes under a name or subject word in the index volume will make this process as systematic and economical of time as it is fascinating to intellectual curiosity. Thus the index volume will serve as a sort of central rotunda, so to speak, making each room in this house of information accessible from every other, and it will matter little at what point we enter. The singer may go in by Volume V, the pianist by Volume VII, the organist by Volume VI: all will eventually penetrate the entire edifice.