Music is dual in its nature; it is material as well as spiritual. Its material side we apprehend through the sense of hearing, and comprehend through the intellect; its spiritual side reaches us through the fancy (or imagination, so it be music of the highest class), and the emotional part of us.

If the scope and capacity of the art, and the evolutionary processes which its history discloses (a record of which is preserved in its nomenclature), are to be understood, it is essential that this duality be kept in view.