Another question is why a composition expresses itself through its particular medium? Why that medium rather than another?

If a masterpiece is transferred from the instrumental medium for which it was conceived to some other, alien medium, it undergoes a curious distortion. Such distortion offers the clearest proof that a musical law is operating in the original: an identity of the idea with its medium. A master’s inner inspiration adapts to his outer terms of reference. Individual instruments lay down individual limitations. If a composer ignores this fact, he can never be certain that his creative aims will ever coincide with the musical results.

Occasionally, a great composer deliberately engineers a collision between the idea and the medium for a special musical purpose. The fugue in Beethoven’s Hammerklavier Sonata, for example, is one of the most physically awkward works to play in the entire piano repertoire. It has been composed against, rather than for, the instrument. Some bars are strictly unplayable, and Beethoven knew it; they contribute to the sense of struggle that is an essential part of musical communication, which is present even in the greatest performance. The orchestration of this fugue by the Austrian composer and conductor Felix Weingartner does a major service to musical aesthetics by providing an alternative musical experience of the same work; but by rendering the difficult easy, his orchestral version robs the music of its basic characteristics. It is a splendid illustration of the way in which, in Beethoven’s original, a creative aim has been identified with a physical limitation.

Thematic chronology

A further question is why the chronology of the themes of a masterpiece cannot be changed. Why does one thematic chronology sound good, another bad? If the movements of a great sonata or a symphony are switched around, the result will be musically inferior. If the themes of one movement are mixed with those from the same work’s companion movements, the result may even be an artistic disaster.

An illuminating exercise in criticism is to “reconstruct” a masterpiece so that its thematic running order is altered; that is, to transfer the first movement’s second subject to the position occupied by the finale’s second subject, and vice versa. Any musician can carry out this simple experiment for himself. Nothing is better calculated to reveal to him the presence of a creative principle of contrast distribution in the original. Given the thousands of different directions in which the material of a work could be unfolded, a master chooses the “right” one, the one that maintains structural tension—and, hence, musical interest. The themes of a masterpiece cannot assume one another’s functions. They are born to fulfill specific roles. They develop out of each other because they create a musical need for each other.

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Economy

Composers through the ages have hinted at a law of economy toward which all great music strives. Brahms, in a characteristic piece of understatement, once said of composing that “the essential thing is that every note should be in its place.” Beethoven expressed the same truth another way. Once, after he had heard the “Funeral March” from the opera Achille by the Italian composer Ferdinand Paer, he observed: “I must compose that!” To “fix” the idea, to define it, to pin it down—both composers felt that this was of the essence. Notes are redundant that do not stand for precisely those musical thoughts they are supposed to express. To have more notes, or less, than are actually required to communicate musical meaning must render such meaning correspondingly obscure. This law may be divided into three subsidiary principles.

First is the principle of identity between the idea and its utterance. There is a concrete musical difference between what a composer intends (the idea) and what he actually says (the utterance). Some musicians contend that the distinction is merely theoretical, that in practice it cannot be made. Fortunately, composers have left ample evidence to the contrary. Consider the act of revision. Revision is an acknowledgment by the composer himself that what he actually wrote was not, on reflection, what he actually meant. Revision is self-criticism. The very word implies that a composer has a re-vision of the work, that he returns to the utterance and modifies it in order to be truer to the idea. Revision can sometimes result in criticism on a grand, creative level. Composers occasionally revise the work of other composers with such effective results that the original composition may be eclipsed by the new version, the “criticism,” often succeeding where the original work failed. Bach’s arrangement (in A minor) for four harpsichords of Vivaldi’s Violin Concerto in B Minor, for example, is more than an adaptation from one medium to another. It is an act of musical criticism par excellence. Vivaldi created the idea. But it was left to Bach to give it complete utterance.

Second is the relation of form and content. Why does music unfold a particular structure? Why that kind of structure rather than another? The textbooks on form remain silent. Yet this is a profound question. It is surely of paramount interest to know why music unrolls in one direction rather than another. Inspired music appears to carry within itself its own blueprint, according to which it propels itself across precise distances and in precise directions. If it is prematurely halted, diverted, or too long continued—all hallmarks of creative immaturity—it loses the sense of punctuality, the feeling of arriving “on time,” the knowledge of being in the right place at the right moment, which characterizes each stage of an emerging structure masterfully handled.

Some musicians have observed that the distinction between form and content is a false one. They rightly argue that no one hears one without the other, that the one is an organic result of the other. Therefore, why not abolish the distinction? They are right in regard to good forms, forms that arise inevitably from the musical material, in which case there is indeed no distinction to abolish. But bad forms, those that are not true to their content, produce a symptomatic division between the inner direction the music was born to follow and the outer direction it was made to follow.

The third subsidiary principle is audibility. The objective of all compositions is to make a total aural impact. There have been some famous miscalculations, intrinsically inaudible passages, which even the most illustrious performance could not render audible. A striking case of inaudibility occurs toward the end of Grieg’s Piano Concerto in A Minor, in which the “big tune” of the finale returns in full orchestral splendour and obliterates the part of the solo pianist. In the concert hall, it is an extraordinary sight to see the soloist racing up and down the keyboard, fortissimo, without producing any sound. The observation is beyond all question and may be checked every time the work is played in public.

In 1937 Schoenberg completed an orchestration of Brahms’s Piano Quartet in G Minor, Opus 25. As a young man, he had regularly participated in performances of the quartet. Time and again, he was bothered by its intermittent inaudibility: the piano tended to swamp the strings. Schoenberg’s orchestration, as he himself claimed, attempted to put matters right. It remains an exercise in musical audibility—one master helping another to communicate. It constitutes an act of criticism on the highest creative level.

Other principles could be formulated to show that a theory of criticism is also a theory of composition. A search for these principles is really a search for the ultimate justification of the feelings of value inspired by great music.