Through the ravishing chamber-music in which, especially in the quintett for oboe, clarinet, horn, fagotto and pianoforte, the splendid treatment of the pianoforte with regard to the wind deserves notice; through all the melodious pieces for piano and violin, the trios, the quartetts; to the numerous smaller clavier-pieces, the fashionable variations, the relics of the suites, the scattered fugues, the fantasies so rich in variety; we follow Mozart to the eighteen pure piano sonatas, which are the very miniature mirror of his unfailing musical invention. We shall treat them in chronological order, for here for the first time we perceive a distinct development which renders such treatment the most natural and advantageous. At first we meet the daring harmonies and enharmonic changes by which every innovator makes himself notorious, and which draw on him the first severe criticisms. But there is not yet the concentration of later works. A light counterpoint runs through the whole, a conscientious treatment of the themes, which bears witness to sound training. A striking feature is the unforced inventiveness in motives, which succeed one another in unfailing profusion. Intellectual themes, as for example in the B flat major, remind us of Philip Emanuel. The form becomes more distinct, the rules of sonata-arrangement more rigid. But it is not till we reach the A minor (1778) that the full brilliancy of form is seen. This piece has all that wonderful proportion and balance even in the smallest parts, which was, and remained, Mozart’s most peculiar characteristic. Proportion in the well-balanced opposition of themes in all three divisions, in the liveliness of the piquant semiquaver runs, which already leave Scarlatti far behind, in the brilliant and yet simple execution of the last movement--proportion, indeed, is everywhere. After 1778 our impressions deepen. The D major is the creation of Mozart’s indestructible caprice. The motives become ever more tuneful, more _speaking_: in the C major we hear the phrases as though sung; we seem to hear words with pauses for breath, as from a distant exquisite opera. The melodies run after each other, and--what is so typical a feature of Mozart--it is by this that our attention is held rather than by any inner development of the themes. [Illustration: Mozart at the age of seven, with his Father and Sister. Engraved 1764, by J. B. Delafosse (b. 1721) after L. C. de Carmontelle (? about 1790).] The A major sonata is an excellent example of this melodic regularity. Its contours are of an unimagined loveliness, and its airs of a magic delicacy. The Turkish March stands out in variegated national colours, far removed from every triviality--if only we give to the Janissary rhythm its full due.