Sonata. The main points of form in the two are similar. The first half of each generally establishes some sort of balance between the principal key and its complementary key, and is then repeated. The second half begins with a passage in which harmonic roots vary on a more extended scale than they do in the first half, proceeding not unfrequently, if the dance be on a large scale, as far as transient modulations; and the last and clenching section is a repetition of some notable feature of the first part. Short as the form is, it admits of a great amount of variety, and it is one of Haydn's triumphs to have endowed his innumerable specimens with ever-changing freshness. The alternation of Minuet and Trio (which are in fact two minuets) is obviously in itself an element of Form, and derives some force from the contrast of the keys in which the two are written, as well as from the contrast of their styles. In Haydn's early Quartets in which he still closely followed the order of the Suites—the two are frequently in the same key, or in major and minor of the same key; but in his later works he takes advantage of contrasts of key and puts his Trio in the Subdominant, or even in the third below, as in the Quartet in G, op. 77. The system of alternating dances after this manner, probably with a view to formal completeness, is evidently of old standing, being found even in Lully's works, and later, as will be more generally remembered by musicians, in Gluck's Iphigenie in Aulis, and in Handel's Overture to Samson. It is chiefly in this respect that we can still trace the relation of the Minuet and Trio to the modern Scherzo, which is its legitimate successor, though in other respects it has not only changed its characteristic rhythms and time, but even its style and form.
The Scherzo is in fact the most free and independent of all the movements of a modern instrumental work, being characterised rather by its sportive and playful style than by any fixed and systematic distribution of subjects and keys. Occasionally it falls into the same order of distribution as a first movement, but there is no necessity whatever that it should do so, and its whole character,—happiest when based upon the incessant repetition in varying lights and circumstances of a strongly rhythmic figure,—is headlong abandon rather than the premeditated design of the serious First movement. Beethoven was the real creator of the modern Scherzo, for all that a few examples exist prior to him; for these are essentially in unsophisticated dance form, and belong to the old order of things, but Beethoven's infinitely various Scherzi are all marked by a certain intimate quality of style, which has been the real starting-point of his successors, rather than any definite formal basis. Mendelssohn created quite a new order of Scherzi of a light, happy, fairylike character, in which his bright genial nature spontaneously expressed itself. But to him the like remark applies, for they are essentially characterised rather by spirit than form. Schumann was fond of putting two Trios in his Scherzi; as in two of his Symphonies, and in the very popular pianoforte Quintet in E♭. This was prefigured in Beethoven by the repetition of the Trio in the Symphonies in A and B♭.
The form of the Slow movement in Sonatas and Symphonies is decidedly variable. It is most commonly based on the same system as a first movement, but owing to the length of time necessary to go through the whole series of sections in the slow tempo, it is common to abbreviate it in some way, as by omitting the portion usually devoted to 'development' and modulation, and passing by a short link only from the presentation of the subjects to their recapitulation as in the slow movement of Beethoven's Sonata in B♭, op. 106, and that of Mozart's Quartet in B♭, No. 3. There are a few instances of Slow movement in Rondo form—as in Mozart's Sonatas in C minor, C major (1778), and D (1777); Beethoven's Sonata pathetique, and that in G (op. 31, No. 1)—and several in the form of a set of Variations. Another happy form of this movement is a species of aria or melody, cast in the old Rondo form, like the example of Lully quoted at the commencement of this article. Of this the beautiful Cavatina in Beethoven's B♭ Quartet (op. 130) is a very fine example, its form being simply a section consisting of the aria or melody continuously developed, followed by a section consisting of impassioned recitative, and concluding with a return to the original section somewhat abbreviated. This form resolves itself practically into the same formal basis as the Minuet and Trio or Scherzo, though so different in character; for it depends almost entirely on the repetition of a long complete section with a contrasting section in the middle. And the same simple basis will be found to predominate very largely in Music, even in such widely different classes as modern Nocturnes, like those of Field and Chopin, and Arias of the time of Handel, of which his 'Waft her, Angels' is a very clear example.
The idea of Variations was very early arrived at by musicians; for Dr. Burney points out that in the age of Queen Elizabeth there was a perfect rage for this kind of music, which consisted 'in multiplying notes, and disguising the melody of an easy, and, generally, well-known air, by every means that a spacca nota, or note-splitter, saw possible.' This primitive kind of variation was still a form of some sort, and is based upon the same principle as that of ground basses, such as are found in Purcell's 'Dido and Æneas,' and were very popular in those days; and of such forms again as Bach's Passacaglia, or Chopin's Berceuse in D♭, or even the wonderful continuous recitative on a constant repetition of a short rhythmic figure in the bass, in Bach's Italian Concerto. In all these cases the principle is that of constant and continuous repetition as a basis for superimposed variety. Into Variations as Variations the question of Form does not enter,
- This form is often called the Lied-form, a term originated by Dr. Marx; but being clearly a misnomer it has not been adopted by the present writer.