Rossini was a composer of the classical period. He was brought up hearing 18th century opera, and much of his best known music is still Classical in style, but he developed a lot as he matured and was writing in a more Romantic way by the end of his career. He gradually stopped writing music which has set numbers all the time: music divided sharply into arias and recitative. His recitative became more expressive and was accompanied by the orchestra instead of by a harpsichord. This helped to make his music more continuous. He did not often write for castrati as they were going out of fashion. The chorus have an important part in the drama of his operas (in 18th century opera they just used to comment on what was going on).