In Lent he gave a concert, at which, following the advice of his patrons, he played selections from "Idomeneo" and his concerto in D major (175 K.), for which he had composed a new rondo (382 K.). The rondo "made a great sensation," and was sent to Salzburg, with a request that it might be treasured as a jewel. "I wrote it especially for myself, and no one else shall play it except my dear sister" (March 2, 1782). As a conclusion he played a fantasia. He had been advised to do this because he would be thereby most certain of outrivalling Clementi, who was giving a concert at about the same time.[52] Mozart had plenty of invitations to play at other people's concerts and in society, on which occasions a new composition had generally to be written. At Auernhammer's concert, for instance, he played with the daughter a "sonata for two" (381 K.), which he {FIRST ATTEMPTS IN VIENNA.} (208) had composed on purpose, and which "was a great success" (November 24, 1781). He wrote easier pieces for his pupils. "I must close my letter" he writes (June 20, 1781), "for I have to prepare some variations for a pupil"; and soon after he wrote to his sister (July 4, 1781): "I have written three airs with variations, which are not worth the trouble of sending alone. I will wait until there is something to accompany them." His time was fully occupied, therefore, and he had no difficulty in proving the injustice of his sister's reproaches to him for not writing oftener (February 13, 1782):--