Prokofiev travelled to London where he met many famous people including Diaghilev who had a very skilled ballet group called Ballets Russes. The composer Igor Stravinsky had been writing ballet music for Diaghilev’s dancers. Prokofiev particularly loved Stravinsky’s "Rite of Spring" and it influenced his music. He wrote an opera "The Gambler" based on the novel by Brusilov but the singers and the orchestra did not understand his music and refused to perform it. One of the first works of Prokofiev to become known all over the world was his First Symphony known as the "Classical Symphony". He made the music sound like that of composers from the Classical period such as Haydn. This symphony is still very popular today.