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
Piano concertos by Wolfgang Amadeus Mozart orchestra" rather than the more obviously "piano" concertos of the nineteenth century (e.g., that of Grieg etc.). Because Mozart was developing the form of his concertos as he wrote them and not following any preconceived "rules" (apart, presumably, from his own judgement of taste), many of the concertos contravene one or other of the generalisations given above. For example, K. 488 in A major lacks new expositional material, and "merely" repeats the preludial material; further, it effectively merges the first ritornello and the middle section, as does K. 449 in E. Several of the later concertos do not hesitate to