Described by the authors, Mozart and DaPonte, gay drama is a work in which drama and tragedy rub elbows with comedy. Using no theme from the opera per se, the faster allegro portion clearly portrays the superhuman restless drive, irresistible temperament and vitality of the hero.
Music is just like sports or anything else in life.
It has rules - or at least it had rules until Beethoven. He upset, ignored, and defied the rules - and music composition continues to change to this day. Franz Joseph Haydn wrote 104 symphonies, but most of them were shorter works than what later composers would write and they were in the accepted format of the time. Beethoven knew the format of the time, but he broke the mold, he changed the prescription. He added parts for instruments never before included in a symphony composition.