 Mozart strives to maintain an ideal balance between a symphony with occasional piano solos and a virtuoso piano fantasia with orchestral accompaniment, twin traps that later composers were not always able to avoid.His resulting solutions are varied (none of the mature series is really similar to any of the others structurally on more than a broad level) and complex.The form of Mozart's piano concerto first movements has generated much discussion, of which modern instances were initiated by the highly influential analysis provided by Tovey in his "Essay".