Appalling F for Fail   As it now stands this article is grossly inadequate and misleading The development at the centre of a sonata structure is in reality a Durchfhrung  ie a leading through various keys The word development is a poor translation of this  and has generated a situation in which foolish people analyse a stretch of music not according to what happens in it but in terms of what this wrong word happens to make them think of As every German muscologist and textbook knows the point of a development section is not various varietites of thematic modification  it is tonal and harmonic instability after the stability of the secondsubject key and before the restoration of the tonic Has noone actually bothered to listen to what does   and doesnt  happen in the included extract ITS MODULATORY AND THATS ALL   This article is too deeply confused to be rescued It should just be deleted Hell it doesnt have a single worthwhile source or any idea about the original German terminology  Pathetic