Any discussion of the art of music,--of its significance in relation to ourselves, of its æsthetic qualities, or of methods of teaching it,--to be comprehensive, must be based on a clear recognition of the one important quality which is inherent in it, which distinguishes it from the other arts and which gives it its peculiar power. Painting and sculpture are definitive. It is not possible to create a great work in either of these mediums without a subject taken from life; for, however imaginative the work may be, it must depict something. In painting, for example, the very soul of a religious belief may shine from the canvas,--as in the Sistine Madonna,--but that belief cannot be there presented without physical embodiment. And when the physical embodiment is reduced to its simplest terms, as in some of Manet’s paintings, there is still the necessity of portrayal; Manet’s wonderful light and opalescent color must fall on an object. Turner paints a mystical landscape, a mythological vale, such as haunts the dreams of poets, but it is impossible for him to produce the illusion _by itself_; the vale is a vale, human beings are there. Sculpture, which makes its effects by the perfection of its rhythms around an axis, and by its shadows,--effects of the most subtle and, at the same time, of the most elemental kind,--it, too, must portray; the emotion must take form and substance, and that form must be drawn from the outward, visible world. In poetry the same limitations exist. It, too, must deal in human life with a certain definiteness. But the greatest poetry is continually struggling to slough off the garment of reality and free the soul from its trammels. It trembles on the verge of music, seeking to find words for what cannot be said, and attaining a great part of its meaning by a sublime euphony. The didactic is its grave.