To a certain degree a mutual understanding is of course indispensable, but it confines itself, as a rule, to an unwilling concession on this or the other side.[40] Music finally assumes the mastery in opera, where it is the actual medium of expression; no one could deny that good music would make the poorest verse pass muster, whereas bad music could not be made acceptable even when "wedded to immortal verse." But the very fact that music appeals direct to the senses gives it an advantage when opposed to poetry, which reaches the imagination through the intellect; just as a poetical description of a work of art falls far short of the effect produced directly on the mind by contemplation of the work itself. Music works on the sense of hearing in an as yet inexplicable manner, rousing emotions and fancies with an instantaneous power surpassing that of poetry. Even if this be disputed, it must be allowed that music does not appeal immediately to the intellect as language does. Even the species of music which is said to occupy the intellect most especially, viz., music in strict forms of counterpoint, does not do it in such a way as to enable the hearer to discover the meaning of the composition by means of its actual utterances; it exercises his intellect otherwise by rousing the desire in him to grasp and hold the artistic forms as such, and the laws upon which they depend.[41] Music must borrow from poetry what it does not possess for itself, namely, the ability to call forth a well-defined image which shall identify itself with the sentiment evoked i by the music and give to this its exact significance. This point is, of course, of special importance in opera, although the fact must not be lost sight of that the stage accessories {DIE ENTFÜHRUNG AUS DEM SERAIL.} (230) and pantomimic representation come greatly to the aid of the music, so that it is quite possible for an audience to follow an opera with interest and gratification without understanding the language in which it is written. This is a further proof that, important as the poetic details doubtless are, the plot and situations are the really essential points. For the paradox that a libretto if it is to be musical cannot be poetical, but can only have certain external forms of poetic delivery, is certainly false. The conditions of poetic delivery and musical execution are essentially the same, and a distinction between them is impossible. But the means of delivery which the poet has at his disposal are manifold and varied, and not all applicable in the same place; if the poet is master of his art, and has a clear conception of what he is striving after, he will know what are the particular means he ought to employ to be in accord with the musical part of the work.[42] Bretzner was very indignant at the proposed alterations in his libretto, and inserted the following notice in the "Berliner Litteratur und Theater-Zeitung" (No. 1783):--