hardly ever to pass the limits of the Tonic and Dominant keys, assists the audience to realise the tonality. Mozart did not follow the example of Haydn in this respect, as many of his symphonies are without Introductions,—especially the well-known ones in C (Jupiter) and G minor. In quintets, quartets, sonatas, and such forms of chamber-music he is also sparing of Introductions, but there is an example of some extent in the quintet for pianoforte and wind in E♭ (Köchel, 452), in which the harmonic successions are simple, and there is a more celebrated one to the string quartet in C, in which the harmonic bases vary more freely than in other examples of that period which can be adduced.
Beethoven began from the first to follow up this point, and it is said that some pedants never forgave him for opening the Introduction to his Symphony in C (No. 1) with chords which appear not to belong to that key. The Symphony in D again (No. 2) has a very important Introduction, in which there is free modulation, such as to B♭ and F, and many passages and figures of great beauty and interest. In the Symphony in B♭ the introductory Adagio is in the highest degree beautiful and impressive, and contains modulation even to the degree of an enharmonic change. In the Symphony in A the idea of the independent Introduction culminates. It has a decidedly appreciable form and two definite subjects. It opens with great dignity and decision in A major, and passes thence to C, the key of the minor third above, in which a clear and beautiful second subject is given; after this the figures of the opening are resumed and a short transition is made back to the original key, passing on from thence to F major, the key of the third below, in which the second subject again appears. From this key the transition to E, the Dominant of the original key, is at the same time easy and natural and sufficiently interesting; and considerable stress being laid upon this note both by its continuance in the harmonies and its reiteration individually, it thoroughly prepares the definite commence- of the Vivace.
In the above instances the Introduction is practically an independent movement, both as regards the substance and the clear division which is made between it and the succeeding movement by a full or half close. In many of his later works Beethoven made an important change in respect of the connection between the Introduction and the movement introduced; by abolishing the marked break of continuity, by the use of figures which are closely related in both, and by carrying the subject matter of the Introduction into the movement which follows.
One of the clearest and most interesting examples of his later treatment of the Introduction is in the first movement of the Sonata in E♭, op. 81a, in which the introductory Adagio opens with the text of the movement, which is constantly reiterated in the 'working out' of the Allegro, and yet more constantly and persistently and with many transformations in the long and beautiful coda. Rubinstein has adopted the same device in his Dramatic Symphony in D minor; in which also the first subject of the first movement proper is a transformed version of the opening subject of the Introduction.
In several of his later Quartets Beethoven makes the most important material of the Introduction appear in the movement which follows it, in different ways as in the Quartet in E♭, op. 127, and that in B♭, op. 130, and A, op. 132, in the last two of which the subjects of the Introduction and the first movement are very closely intermixed. In the E♭ Concerto also the Introduction reappears with certain variations of detail in the latter part of the movement previous to the 'recapitulation' of the subject. In its intimate connection with the movement which follows it, the Introduction to the first movement of the 9th Symphony is most remarkable. It commences mysteriously with the open fifth of the Dominant, into which the first rhythms of the first subject begin to drop, at first sparsely, like hints of what is to come, then closer and closer, and louder and louder, till the complete subject bursts in in full grandeur with the Tonic chord. In this case the introductory form reappears in the course of the movement, and also briefly in the discussion of the previous themes which immediately precedes the commencement of the vocal portion of the work.
After Beethoven no composer has grasped the idea of intimately connecting the Introduction with the work which it introduces more successfully than Schumann, and many of the examples in his works are highly interesting and beautiful. In the Symphony in C, for instance, a striking figure of the opening reappears in the first movement, in the scherzo, and in the last movement. In the Symphony in D [App. p.685 "minor"], in which all the movements are closely connected, the introductory phrases are imported into the Romanze, where they occupy no unimportant position. In his Sonata in D minor, for violin and pianoforte, op. 121, the Introduction proposes in broad and clear outlines the first subject of the succeeding allegro, in which it is stated with greater elaboration. The Overture to Manfred affords another very interesting specimen of Schumann's treatment of the Introduction. It opens with three abrupt chords in quick tempo, after which a slow tempo is assumed, and out of a sad and mysterious commencement the chief subject of the Overture proper is made by degrees to emerge. An earlier analogue to this is the Introduction to Beethoven's Egmont Overture, in which one of the chief figures of the first subject of the overture seems to grow out of the latter part of the introduction.
Of all forms of musical composition none are more frequently preceded by an Introduction than overtures; the two above mentioned, and such superb examples as those in the Overtures to Leonora Nos. 2 and 3, and to Coriolan, and such well-known ones as those to Weber's Der Freischütz and Oberon, Schumann's Genoveva, and Mendelssohn's Ruy Blas, will serve to illustrate this fact.