Keyboard concertos by Johann Sebastian Bach soloists, were all adapted into harpsichord concertos by the composer, BWV 1058, 1054 and 1062 respectively. It is often assumed that Bach's extant violin concertos were written in his Köthen period (1717–1723): it can however not be proven from documentary evidence that any of them existed prior to around 1730. In September 1725 Bach performed organ music, accompanied by other instruments, in Dresden. The works he performed there have not been identified. More than a year later he composed several cantatas with an organ obligato part. Several movements of such cantatas were derived from earlier lost concertos, and resurfaced in
Piano concertos by Wolfgang Amadeus Mozart of "fiddling" with all the themes, instead is left with the ritornellic impression: Mozart truly uses "art to conceal art". One further point of great importance is the interaction between piano and orchestra. In the earlier concertos, such as the not totally successful No. 13 in C major, and even more so, perforce, in the concertos for two and three pianos, the interaction between the two is limited, but the later concertos develop the subtle relations between them to a high degree; for example, in No. 16, K. 451. His later concertos are truly described as concertos for "piano and