I still have 2 concertos to write to complete my subscription concerts [Mozart wrote three piano concertos for these subscription concerts: K413-K415]. These concertos are a happy medium between what's too difficult and too easy. They are brilliant, pleasing to the ear, natural without becoming vacuous. There are passages here and there that only connoisseurs can fully appreciate, yet the common listener will find them satisfying as well, although without knowing why.
[I]n addition [to the two piano concertos and a piano version of the Singspiel, Die Entführung aus dem Serail], I'm working on a quite difficult assignment; namely, an Ode to Gibraltar by [Johann Michael] Denis. It's a commission by a Hungarian Lady who wants to keep this a secret and present it to Denis as a tribute. The ode is sublime, beautiful, anything you want, but it's too exaggerated and bombastic for my fastidious ears. But what is one to do! The middle thing — the truth in all things — is no longer known and appreciated. To earn applause, one has to compose things that are so simpleminded that a coachman can sing them after hearing them just once, or so complicated that they please precisely because no sensible person can understand them.
—Wolfgang Amadeus Mozart, in a letter to his father, 28 December 1782