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 elevated to the most prominent position among the instruments. These works, with their alternation of orchestral "tuttis" and passages for solo display, in turn owe their structure to the tradition of Baroque operatic arias, from which the first movements of Mozart's piano concertos inherited their basic ritornello form. A similar structure can also be seen in the violin concerti of, for example, Vivaldi, who established the form, along with the three-movement concerto structure, and Viotti, wherein the concerto is divided into six sections. The keyboard parts of the concertos were almost invariably based on material presented in the ritornelli, and