The 1870s and 1880s were a period of remarkable productivity, during which Saint-Saens wrote much of his best and enduringly popular music, including the opera Samson et Dalila (finished in 1877), the Organ Symphony (1886), several tone poems, a dozen concerted works, and a clutch of chamber works, including Le carnaval des animaux (The Carnival of the Animals', 1886).