Emanuel Schikaneder heard this, he called down into the orchestra, "Hey, Mozart! That's no good, the music must express greater astonishment. They must both stare dumbly at each other, then Papageno must begin to stammer: 'Pa-papapa-pa-pa'; Papagena must repeat that until both of them finally get the whole name out. Mozart followed the advice, and in this form the duet always had to be repeated." Castelli adds that the March of the Priests which opens the second act was also a suggestion of Schikaneder's, added to the opera at the last minute by Mozart. These stories are not accepted as necessarily true
Piano concertos by Wolfgang Amadeus Mozart it was probably J.C. Bach, whom Mozart admired, who introduced the structural innovation of allowing the keyboard to introduce new thematic material in its first entry. Concertos Nos 1–4 (K. 37, 39, 40 and 41) are orchestral and keyboard arrangements of sonata movements by other composers. The next three concertos (K. 107/1, 2 and 3), which are not numbered, are arrangements of piano sonatas by J.C. Bach (Op 5. Nos. 2, 3, and 4, all composed by 1766). Based on handwriting analysis of the autographs they are believed to date from 1771–72. Concerto No. 5, K. 175 from 1773 was