rendering them.’[58] Ries and other artists have also borne testimony to his skill, wealth of imagery and inexhaustible fertility of ideas. Grove says: ‘He extemporized in regular form; and his variations, when he treated a theme in that way, were not mere alterations of figure, but real developments and elaborations of the subject.’ In close connection with his work as pianist, and exercising a powerful influence not only upon Beethoven but also upon all later composers, was the mechanical development of the pianoforte. The clavichord and clavicembalo, which had occupied a modest place during the eighteenth century merely as accompanying instruments to string or wind music, were now gradually replaced by the _Hammer-clavier_, as it was called, which, by the middle of the century, began to be considered seriously as a solo instrument of remarkable powers. Important piano manufacturers, such as Silbermann in Strassburg, Späth in Regensburg, Stein in Augsburg, Broadwood in London, and Érard in Paris, did much to bring about the perfection of the instrument and so indirectly assisted in the development of pianoforte music. In 1747 Sebastian Bach had played a Silbermann piano before Frederick the Great in Potsdam, but the important development came after the middle of the century. In London, in 1768, Johann Christian Bach used the pianoforte for the first time in a public concert, and we know that Mozart possessed instruments both from Späth and Stein, and that in 1779 some of his work was published ‘for Clavier or Pianoforte.’ An immediate consequence of this sudden rise of the pianoforte into popularity was, of course, the appearance of a new musical literature adapted to the peculiarities of the instrument. Among the first of the technical students of the pianoforte was Muzio Clementi,[59] whose _Gradus ad Parnassum_, or hundred exercises ‘upon the art of playing the pianoforte in a severe and elegant style’ made a deep impression upon the rising generation of musicians and are still considered of the highest educational value. Some of these exercises were published as early as 1784, though the collection was not made until 1817. An extract from the writing of one of Clementi’s best pupils throws some light upon the standard of taste in regard to pianoforte playing which prevailed in Beethoven’s early days. He says: ‘I asked Clementi whether, in 1781, he had begun to treat the instrument in his present (1806) style. He answered _no_, and added that in those early days he had cultivated a more brilliant execution, especially in double stops, hardly known then, and in extemporized cadenzas, and that he had subsequently achieved a more melodic and noble style of performance after listening attentively to famous singers, and also by means of the perfected mechanism of English pianos, the construction of which formerly stood in the way of a cantabile and legato style of playing.’ It is evident that Beethoven came upon the scene as pianoforte player