Of all the arts, music is practised most and thought about least. Why this should be the case may be explained on several grounds. A sweet mystery enshrouds the nature of music. Its material part is subtle and elusive. To master it on its technical side alone costs a vast expenditure of time, patience, and industry. But since it is, in one manifestation or another, the most popular of the arts, and one the enjoyment of which is conditioned in a peculiar degree on love, it remains passing strange that the indifference touching its nature and elements, and the character of the phenomena which produce it, or are produced by it, is so general. I do not recall that anybody has ever tried to ground this popular ignorance touching an art of which, by right of birth, everybody is a critic. The unamiable nature of the task, of which I am keenly conscious, has probably been a bar to such an undertaking. But a frank diagnosis must precede the discovery of a cure for every disease, and I have undertaken to point out a way in which this grievous ailment in the social body may at least be lessened.