His compositions give only a slight idea of what the range of his playing was. He seems to have moved people most at times when he improvised. This he would often do in public, according to the custom of the day; but in private, too, he would often go to his piano and pour his soul out hour after hour through the night in improvised music of strange and unusual power. Something of the quality of these outpourings seems to have been preserved in the fantasia in C minor. The sonatas and rondos have little of it. Neither have the concertos. Franz Niemetschek, one of his most devoted friends and author of the first of his biographies, said, as an old man, that if he dared ask the Almighty for one more earthly joy, it would be that he might once again before he died hear Mozart improvise. The improvisations of Beethoven, marvellous as they were, never took just the place of Mozart’s in the minds of those who had been privileged to hear the younger man as well.
Mozart did not compose his piano music at the piano, as Schumann and Chopin did. The improvisations were not remembered later and put down in form upon paper. They seem to have been something apart from his composing. He wrote music away from the piano, at his desk, as most people write letters—in the words of his wife. Most of the sonatas, too, were written for the benefit of pupils. Few of them make actually trying demands upon technical brilliance. Their great difficulty is more than technical, or than what is commonly regarded as technical—strength, velocity, and endurance. Yet no music more instantly lays bare any lack of evenness or any stiffness in the fingers. Mozart cared little for a brilliant style. His opinion of Clementi has already been mentioned. He preferred rather a moderate than an extremely rapid tempo, condemned severely any inaccuracy or carelessness, likewise any lack of clearness in rhythm. But, above all, he laid emphasis on a beautiful and singing quality of tone.
His avoidance rather than cultivation of brilliancy alone makes his music often suggest the harpsichord. There is an absence of the technical devices then new, which have since become thoroughly associated with the pianoforte style. Yet from 1777 Mozart devoted himself to the pianoforte. An instrument made especially for him, which he invariably used in his many concerts in Vienna, has been preserved. The keyboard has a range of five octaves, from the F below the bass staff to the F above the treble staff. The action is very light, the tone rather sharp and strong. It can be damped, or softened, by means of a stop which pulls a strip of felt into position between the strings and the hammers.
Concerning the pianoforte sonatas it may be said again that few depart from a normal, prevailing mood. Some are exceptional. Knowing his great gift of improvising and how rich and varied his improvisations were, it is perhaps a temptation to read into them more definite emotions than are really implied. Yet it is easy to pick from the later sonatas at least three which not only differ considerably from the earlier sonatas, but differ likewise from each other. Nevertheless, two or three traits are common to them all. They mark Mozart’s sonatas distinctly from Haydn’s and, indeed, from all other sonatas.
First, there is rare melodiousness about them all. The quality of the melodies is hard to analyze. There is little savor of the folk-song, as there is in many of Haydn’s melodies. They are not so clearly cut, not, in a way, of such solid stuff. Neither, on the other hand, have they a peculiar germinating vigor which we associate with Beethoven. They seem to spin themselves as the music moves along. The movements seem to flow rather than grow. Mozart was none the less a great contrapuntist, one of the greatest among composers. But his music seems strangely to pass through counterpoint, not to be built up of it. It has therefore a quality of litheness or supple flexibility which distinguishes it from that of other composers and gives it a preëminent grace. In this regard it is akin only to the music of Couperin and Chopin.
In the second place, the harmonic coloring is subtle and suggestive. His music seems to play about harmonies rather than with them. The simplest chords and modulations have a sort of shimmer. An instance in orchestral music comes to mind—the second themes in both the first and last movements of the inspired symphony in G minor, particularly the treatment of the second theme in the restatement section of the last movement. The effect is due largely to the chromatic half-steps through which his melodies glide, noticeably into cadences, and to the same chromatic hovering about tonic, dominant and subdominant chords. Oftener than not the fine thread of his melody only grazes the notes proper to its harmony, touching just above or below them in swift, light dissonances. Frequently the harmonic foundation is of the simplest kind. Modulations to remote keys or vague drifting of the whole harmonic fabric, such as one finds, for instance, in the first pages of the Fantasia in C minor, are rare. Usually the harmonic foundation is astonishingly simple. It is the wholly charming unwillingness of the melodies to be flatly chained to it that gives the whole such an elusive color.
There is a wealth of passing notes, of anticipations and suspensions, of every device which may aid melody to belie its unavoidable relations to harmony. These take from most of his pianoforte music all trace of commonplaceness. Most of it has a graceful distinction which we may call style. Take even the opening theme of the great sonata in A minor. The nature of the theme is bold and declamatory; yet the very first note avoids an unequivocal allegiance to the harmony by a D-sharp. Or observe in the last movement of the sonata in C minor (K. 457) how the short phrases of the melody not only anticipate the harmony in beginning, but delay acknowledging it again and again.
In the third place, the scoring of Mozart’s sonatas is usually lighter than that of Haydn’s. We have to do with a finer set of fingers, for one thing, which are unexcelled in lightness and sweetness of touch, fingers which prefer to suggest oftener than to declaim. The treatment of inner voices is more airy. One thinks again of Couperin and even more of Chopin. There is a better understanding of pianoforte effects, not effects of brilliance but of delicate sonority combined with grace. The last movement of the sonata in A minor just mentioned, is a masterpiece of style, and yet for the most part is hardly more than a whisper of sound. The passage work in the last movement of a beautiful sonata in F major (K. 332), the chord figures of the Piu allegro section of the Fantasia, even the F-sharp minor section of the familiar Alla Turca are the work of a man with an unusually fine sense of what fitted the pianoforte. Mozart also expected more of the left hand than Haydn expected. In all his pianoforte music there is more delicacy than there is in Haydn’s, more sophistication, too, if you will. It is more difficult to play.
Of the many sonatas, rondos and fantasias only a few may be discussed in detail. Three sonatas written before Mozart settled in Vienna, in 1781, are very fine. These are in A minor (K. 310), in A major (K. 331) and in F major (K. 332). That in A minor was written in 1778. The first movement is more stentorian than Mozart’s music usually is. It is dominated by a strong rhythmical motive throughout, used with fiery effect in the development section over a series of rumbling pedal points. There is something assertive and martial about it, like the ring of trumpets over a great confusion. The second theme seems to be but an expression of energy in more civilian strain. It is perilously near virtuoso stuff; but the movement as a whole is splendid by reason of its force. It is Mozart in a very unusual mood, however.
The second movement is a picture in music, according to Mozart himself, of a charming little girl, who has ‘a staid manner and a great deal of sense for her age.’ Yet something of the boldness of the first movement still lingers. The mood is beautifully lyrical and poetic, the style, however, very free and broad. It lacks the intimate tenderness of most of Mozart’s slow movements. The last movement is magical. The fine, delicate scoring, the short phrases, as it were breathless, the beautiful shifting of harmonies, the constantly restless unvaried movement, weave a texture of music that must make us ever wonder at the nature of the mysterious, elusive spirit that whispers all but unheard behind so much of Mozart’s music.