What the average reader can get from his study of the theoretical portions of 'The Art of Music’ will depend largely on his instinctive sense of the larger bearing of technical facts. Studied with pedantic insistence of detail harmony is a dry subject; studied with an imagination eager for the light it throws on general æsthetic questions it proves unexpectedly illuminating. Harmony describes the material available to the musician; it is, we might say, the dictionary from which each composer chooses the words he needs to express his thought; and to study it is therefore for the lover of music much what it is for the lover of literature to study the vocabularies of his favorite authors--the derivations of the words, their ancient associations, the flavors which cling about them. Just as Sir Thomas Browne has his special words, noble-sounding, many-syllabled, and his special forms of sentence that roll grandly off the tongue, and as Keats finds in the same English a completely different instrument, capable of romantic utterance and full of elusive suggestion: so the harmony of Bach is not the harmony of Schumann, although it is made out of the same notes and even many of the same chords. Indeed, the very same chord is not the same in effect, in style, when used in the context of two composers, or even of one composer in two different moods; a chord is a chameleon that takes the color of its surroundings. How full of sadness, of infinite resignation, is the first B flat chord in the Adagio of the Ninth Symphony! How the very same B flat chord pulsates with energy in the Allegro of the Fourth! The study of the action and reaction of harmony and style is a fascinating one, in spite of its difficulty--one on which books might be written, as many have been on the choice of words in literature.