And yet, justifiable as their feeling was, indispensable as their labors were to that development without which the expressive power of music would itself have remained rudimentary, it is not to their view, but to a more universal one, that we must look to find a rounded theory of expression and form. If it be a mistake to neglect the latter for the former, as they well saw, it is equally a mistake to prize form with too exclusive an enthusiasm. For beauty is itself one of the most potent means of expression. Our minds are not made up of hermetic compartments, but are so permeable, so conductive, that an eloquent thing is made more eloquent by being also beautiful. The impression of beauty reverberates endlessly, intensifying all that is associated with it. The general atmosphere transfigures every feature. If the whole is fair, no detail will be entirely without its appeal to our kindled imaginations, but if the whole is formless, no single phrase, however impassioned, can affect us very deeply. The truth is, then, that form and expression in music are as essential to each other as objects and light in the world of vision. No radiance of illumination will satisfy the eye if there is nothing to see, and, on the other hand, the loveliest things will give little pleasure in the dark. To be beautiful they must be suffused in light. Similarly the phrases of music, to be truly moving, must be suffused in beauty. The greatest masters clearly realized this. Bach in his masterpieces, Beethoven nearly always, and Brahms in his inspired hours, acted on the principle that the two elements must exist side by side, subtly and potently reacting upon each other. Their practice, indeed, unanimously confirms the theory of musical effect which has now been briefly sketched, and which may be more briefly summarized before we pass on to deduce from it some general canons of appreciation and criticism.