in their power of rapid movement. Their union enables them to fulfil the demands of complete harmonies, and to compensate by increase of freedom and fulness for the advantages which the pianoforte possesses as a solo instrument. The quartet is therefore particularly well adapted both for the polyphonic and the homophonie style of composition. The varieties of tone of the instruments among each other, and of each in different keys, further increases their capacity for expression, the nuances of tone-colouring appearing to belong to the nature of stringed instruments. Thus the material sound elements of the string quartet are singularly uniform, at the same time that they allow free scope to the individual movement of the component parts. The beginning of the andante of the E flat major quartet (428 K.) will suffice to show how entirely different an effect is given by a mere difference in the position of the parts. The value which Mozart set upon the uniformity of the naturally beautiful sound effects of stringed instruments may be inferred from the fact that he seldom attempted interference with it as a device for pleasing the ear. Pizzicato passages occur only three times--in the trio of the D minor quartet (421 K.), of the C major quintet (515 K.), and of the clarinet quintet (581 K.)--and each time as the gentlest form of accompaniment to a tender melody. He was not prone either to emphasise bass passages by pizzicato, and has done so only in the second adagio of the G minor quintet (516 K.) and in the first movement of the horn quintet (407 K.). Nor is the muting, formerly so frequent, made use of except in the first adagio of the G minor quartet and in the larghetto of the clarinet quintet. It need scarcely be said that an equal amount of technical execution and musical proficiency was presupposed in each of the performers. This is especially noticeable in the treatment of the violoncello. It is not only put on a level with the other instruments as to execution, but its many-sided character receives due recognition, and it is raised from the limited sphere of a bass part into one of complete independence. The favourite comparison of the quartet with a conversation between four intellectual persons holds good in some {MOZART'S STRING QUARTETS.} (9)