Only one clavier work of special significance, apart from the sonatas, remains to be mentioned. This is a very beautiful series of variations on a theme in F minor. They present, of course, the familiar features of Haydn’s style, clear and ‘economic’ part-writing, perfect balance and lucidity in form, abrupt, unprepared chords, furnishing what Hadow has aptly called ‘points of color’; and still, smooth, chromatic progressions which are somehow naïve. The theme itself is in two sections, with a ‘trio’ section in F major, full of ascending and descending arpeggio figures which seem in Haydn’s music like the warble of a bird’s song, odd little darts and flurries of sound. There is over the whole a changing light of plaintive and gay which is rather different from the perpetual sunshine of the sonatas. It is needless to say that the theme undergoes no such metamorphosis in the course of the variations as Bach’s theme in his Goldberg Variations. The accompaniment may be said to remain practically the same throughout the set. The first variation leads the melody through half-steps, in syncopation, and numerous trills are brought in to beautify the almost too ingenuous major section. In the second variation the melody is dissolved, so to speak, into a clear stream of rapid counterpoint which curves and frets above and below the familiar accompaniment. The final restatement of the theme leads by abrupt soft modulations into a long coda in which traces of the theme still linger. The whole set makes up a masterpiece in pianoforte literature, and may be ranked as one of the most beautiful pieces of music in the variation form. II Mozart’s keyboard music is astonishingly different from Haydn’s. Because both men have fallen into the obscurity of the same shadow, one is likely to speak of them as if both were but a part of one whole. The differences between them are not merely matters of detail. In fact they may resemble each other more in detail than in general qualities. The spirit of Mozart’s music is wholly different from the spirit of Haydn’s. If with Haydn we may associate a frank good nature and something of the peasant’s sturdiness, in Mozart’s music we have to do with something far more subtle, far more graceful, and almost wholly elusive. It has been said of Mozart’s music that its inherent vitality is all-sufficient to a listener. In other words, there is neither any need nor any desire to interpret it, either in terms of another art or as an expression or a symbol of human emotion. It is perhaps unique in being sheer sound and nothing else. It is the thinnest gossamer spun between our ears and stillness. It is of all music the most ethereal, the most spiritual, one might almost say the least audible.