where the long horizontal line represents the main key, the
short horizontal lines represent a second key, the perpendicular
line represents the division into two portions,[1] and the letters
represent the phrases. This form is often typified in the compass
of a single melody without change of key or marked division,
as in that beautiful English tune “Barbara Allen,” where
the half-close on the dominant in the fourth bar is symmetrically
reproduced as the full close on the tonic at the end (see Melody,
example 1). On a larger scale it admits of great variety and
elaboration, but the style of the classical suite never allows it to
become much more than the musical analogue of a pattern on a
plate. The passage from the material in the main key to that in
the foreign key (from A to B in the above diagram) is continuous
and unnoticeable, nor is the second part of the design which
leads to the return of B in the tonic noticeably different in style
or movement from the earlier part. It has a slightly greater
range of key, for the sake of variety, but no striking contrast.
Lastly, the rhythms, and such texture as is necessary to keep
the details alive, are uniform throughout.
Now, the essential advance shown by the true sonata forms involves a direct denial of all these features of the suite style. No doubt one natural consequence of working on a larger scale is that the sonata composer tends to use several contrasting themes where the suite composer used only one; and an equally natural consequence is that the shape itself is almost invariably amplified by the introduction of a recapitulation of A as well as of B in the tonic, so that our diagram would become modified into the following:—
But these facts do not constitute a vital difference between sonata and suite forms. They do not, for instance, enable composers like Boccherini and the later Italian violin writers to emancipate themselves from the influence of the suite forms, though the designs may be enlarged beyond the bursting point. The real difference lies, indeed, in every category of the art, but primarily in a variety of rhythm that carries with it an entirely new sense of motion, and enables music to become not only, as hitherto, architectural in grandeur and decorative in detail, but dramatic in range. The gigue of Bach’s C major suite for violoncello, and the allemande of his D major clavier partita, will show that the suite forms were amply capable of digesting a non-polyphonic style and a group of several contrasted themes; but they still show the uniformity of rhythm and texture which confines them to the older world in which visible symmetry of form is admissible only on a small scale. Haydn can write a movement, perhaps shorter than some of Bach’s larger dance movements, containing only one theme and mainly polyphonic in texture, as in the finale of his tiny string quartet in D minor, Op. 42; but the transformations of his one theme will be contrasted in structure, the changes of rhythm will be a continual surprise, the passage from the first key to the second will be important and emphatic, and at every point the difference in scope between his sonata music and Bach’s suite music will be as radical as that between drama and lyric. The process of this change was gradual; indeed, no artistic revolution of such importance can ever have been accomplished more smoothly and rapidly. Yet Philipp Emmanuel Bach, the first to realize the essentials of the new style, obtained his object only at the cost of older elements that are essential to artistic completeness. And Haydn himself was hardly able to reinfuse such vitality of texture as would give the new form permanent value, before he was forty years of age.
Haydn’s earlier string quartets, from Op. 1 to Op. 33, present one of the most fascinating spectacles of historical development in all music. He was content to begin at a lower level of brilliance than some of his contemporaries; because from the outset his object was the true possibilities of the new style, and no luxuriance of colour could blind him to the lifelessness of an art that is merely suite-form spun out. Haydn’s earliest quick movements in sonata forms are often as short as any suite movement, except when he writes for orchestra, where he is influenced by the style of the operatic overture as we find it in Gluck and in the symphonies of Philipp Emmanuel Bach In his slow movements he at first more often than not worked in the style and form of the operatic aria; and in so mature a piece as the quartet in G major, Op. 17, No. 5, he not only endorses Philipp Emmanuel Bach’s evident conviction that operatic recitative is within the scope of the sonata, but convinces us that he is right. It was easy for the early composers of sonatas to introduce theatrical features into their instrumental music; for the very fact that the sonata forms were in polyphonic days the forms of lighter music is a consequence of their original identity with the forms of stage-music and dance (see Overture and Symphony). But it needed a very great composer to realize not only the radically dramatic character of a sonata form in which the rhythm and texture is emancipated from the metrical bondage of the suite, but also its true limitations as pure instrumental music. As Haydn’s work proceeded, so did the freedom of his rhythm and its consequent inner dramatic life increase; while the external operatic influences soon disappeared, not so much because they were out of place, as because opera itself “paled its ineffectual fires” in the daylight of the pure instrumental drama with its incomparably swifter and terser action. Polyphony, on the other hand, steadily increased, and was so openly encouraged that in the first set of Haydn’s quartets which is entirely free from archaism (Op. 20) three of the finales are regular fugues. And from that time onward there is hardly a work of Haydn’s in which highly organised fugato passages are not a frequent means of contrast.
2. The Sonata Form.—In the last-mentioned quartets . of Haydn and the works of Mozart’s boyhood, the normal sonata form, as we now accept it, is firmly established, and may be represented as follows:—
This diagram is, no doubt, equally true of Philipp Emmanuel Bach’s form; and thus we see how little the external shape of a movement tells us as to the ripeness or genuineness of the specimen. Apart from this, much confusion of thought is caused by the unfortunate terms “first and second subject,” which have misled not only many teachers but nearly all pseudo-classical composers into regarding the exposition of the movement as consisting essentially of two themes expanded to the requisite size by appropriate discourse. When we use the terms “first and second subject,” then, let us be understood to mean any number of different themes, in any variety of proportion, but separable into two groups of which the first is in the tonic while the second is in another related key, which is called the complementary key. The exposition of a movement in sonata form contains, then, these two “subjects” and represents these two keys; and unless the work is too large or too emotional for merely decorative emphasis, the exposition is generally repeated. Then the development follows. It is normally founded on the materials of the exposition, but neither confines itself steadily to any key nor leaves its material as it found it. On the contrary, its function is to provide a wide range of modulation, and to put the materials into fresh light by regrouping them (see Melody, examples 2–7). It cannot be too strongly insisted that in the sonata forms there are no rules whatever for the number of themes and their relative prominence among themselves and in their development. After the development the first subject returns in the tonic, with an effect which, after so many changes of key, is always reassuring as regards
- ↑ In all stages of development it has been usual to repeat at least the first portion. The repetition is indicated by a sign and may be ignored in analysis, though Haydn, Beethoven and Brahms have sometimes produced special effects by it. The repetition of the second part is now obsolete, and that of the first nearly so.
