After graduating in 1921, Balanchine enrolled in the Petrograd Conservatory while working in the corps de ballet at the State Academic Theater for Opera and Ballet (formerly the State Theater of Opera and Ballet and known as the Mariinsky Ballet). His studies at the conservatory included advanced piano, music theory, counterpoint, harmony, and composition. Balanchine graduated from the conservatory during 1923, and danced as a member of the corps until 1924. While still in his teens, Balanchine choreographed his first work, a pas de deux named "La Nuit" (1920, music by Anton Rubinstein). This was followed by another duet, "Enigma", with the dancers in bare feet rather than ballet shoes. During 1923, with fellow dancers, Balanchine formed a small ensemble, the Young Ballet.