I had never heard so delicate and graceful an execution. I was especially delighted with an adagio, and with several of his extemporised variations. The Emperor gave the subject, and we varied it, alternately accompanying each other. On the other hand, Mozart's judgment of Clementi was sharp and severe:-- Clementi is a good player, and that is all one can say. He plays well as far as the execution of his right hand is concerned. His forte lies in passages in thirds. But he has not an atom of taste or feeling, in fact he is a mere mechanist. When his sister in Salzburg had made acquaintance with Clementi's sonatas, he wrote to her (June 7, 1783):-- Now I must say a word to my sister on the subject of Clementi's sonatas. Every one who plays them must be aware that as compositions they are valueless. There are no striking passages, except the sixths and octaves, and I should strongly advise you not to be too much taken with these, for they are the ruin of a firm and quiet hand, and would soon deprive it of its lightness, flexibility, and flowing rapidity. For what is the object of these passages after all? They must be executed with the utmost rapidity (which not even Clementi himself can accomplish), and a lamentable hash is the result--nothing else in the world, Clementi is a charlatan, _like all the Italians!_ He writes _presto_ on a sonata, or even _prestissimo or alia breve_, and plays it _allegro_ in three-four time. I have heard him do it! What he does {STRACK AND COURT MUSIC.} (201) really well are passages in thirds--he worked at them day and night in London--but he can do nothing else, and he has not the least execution or taste, and far less any sentiment in his playing.[36] In justification of this censure, Berger mentions Clementi having told him that, at the time of which Mozart writes, he devoted his attention to brilliant execution, and in particular to double runs and extemporised passages; it was only later that he adopted a more expressive style, which was perfected by the study of the best vocal music of the day, and by the gradual improvements made in the instrument known as the English pianoforte, the primitive construction of which had been too defective to allow of an expressive legato execution. Berger remarks further that Mozart's honourable and upright character prevents any suspicion of underhand motives for the severity of his judgment.