One of the most important French composers, Jean-PhilippeRameauwas a contemporary of Handel, Bach and Domenico Scarlatti. Rameauís first job was an organist at Clermont Cathedral. Supported by a patronage of a rich amateur, Rameau later dedicated his activity entirely to the composition of opera, harpsichord and other instruments. Rameau was a very important theorist. His Treatise on Harmony was the most significant research of the time.