Undoubtedly music gives greater pleasure to more people than does any other art, and probably this enjoyment is of a more subtle and pervading nature; every one enjoys music in some degree, and many enjoy it supremely. Sound is also of the greatest practical importance; we rely upon it continually for the protection of our lives, and through talking, which is but making sounds according to formula, we receive information and entertainment. These facts give ample justification for studying the nature of sound, the material out of which music and speech are made.