IV. THE HARMONIC PLAN.
The recurrence in the same key of the theme in the variation form gives to it a certain monotony of harmonization unless the episodes are treated with great harmonic freedom. As was pointed out in Chapter II, harmony sometimes becomes an important element of structure, particularly in the rondo and variation forms, and in Haydn's and Mozart's variations the harmonic plan is not sufficiently varied to provide this much needed contrast. Beethoven, however, always much more free in the use of modulation than his predecessors, imparts to these variations almost at the outset great variety of key, and in all his episodes ranges freely about, unhampered by limitations. In measure 28, for example, he suddenly starts towards the key of B-flat minor, only to emerge a moment later in C-major. The passage, beginning at measure 39, not only provides that relief from too great insistence on melody which we have already referred to as characteristic of his episodes, but its harmonies are purposely vague, leaving us in doubt until the last moment as to their ultimate conclusion. An interesting and beautiful effect is again produced, at measures 167-177, by the changes of key, while the scale passages that follow introduce further harmonic variety. At measure 206 begins a passage that seems to intend the key of D-flat, but again our expectations are not realized. So that the total impression we receive from the harmony of this movement is of a more complete unity and variety than is produced by the themes themselves.
It must also be noted in general that this freedom of harmony is one of the signs of advancement in the art of music, and that at the present time the combination of chords is much less restricted than was the case in Beethoven's day. And this steady advance has been as steadily opposed by theorists. When we remember that Monteverde (1567-1643) was bitterly criticised for introducing in a chord the unprepared dominant seventh, making thereby a dissonance almost as familiar to modern ears as is the simple major triad—we can easily realize how difficult it was for people in Beethoven's time to understand his far-reaching modulations. The steady progress is further illustrated by Wagner's music-dramas, which were considered when they first appeared as almost cacophonous in their harmonization, but which now seem perfectly simple and normal.