The great value of the orchestra is its power of uttering the _unspeakable_, _i.e._ that which is unutterable through the organ of the understanding. It may do this in three ways--by its organic alliance with _gesture_, by bringing up the _remembrance_ of an emotion, when the singer is not giving voice to it, and by giving a foreboding of moods as yet unspoken.
All the constituents of drama have now been enumerated. It only remains to consider how they are to be knit together into a single form corresponding to the single substance. Just as the poet obtained his action by compressing all the motives into an easily comprehended content, so, for the realisation of this action, must he proceed with the composition on the same principles. The expression, like the action, must be free from the accidental, the contingent, the superfluous.
We approach the drama in a mood of expectancy, that is ministered to by the orchestra in its quality of a producer of foreboding--although this preliminary utterance of the orchestra must by no means be interpreted to mean the ordinary "overture." This expectancy is afterwards satisfied by the word-speech of the performer, lifted into the higher emotional sphere of tone-speech. The unity of content in the drama must be made evident in a unity of artistic expression; that is, the expression "must convey to the feeling the most comprehensive aim of the poetic understanding." Wherever the word-speech approaches the language of ordinary life--the organ of understanding--the orchestra must keep the expression still on the higher plane, by means of its faculty of conveying foreboding or remembrance. Yet it must assume this function not through the mere caprice of the musician, but in obedience only to the poet's aim. Unity of content and unity of expression must go hand in hand. These melodic moments of the orchestra will take their rise only from the _weightiest motives of the drama_, which are the pillars of the edifice. In this way a binding principle of musical form may be obtained which springs directly from the poetic aim, and far surpasses the arbitrary, _merely musical_ form of the old opera, which was loose, uncentralised, and inorganic.