Couperin published his two organ Masses (for the Parishes, and for the Convents) in 1690, at the age of 22. They are here presented independently from the alternating plainchant which was sung during Mass. Though intended primarily to illustrate the meaning of the liturgical text, the music displays skilful use of polyphonic texture and borrowings from secular styles, revealing a remarkable freshness of inspiration. The historical François-Henri Clicquot great organ of Poitiers Cathedral is the most authentic great classical organ of France and among the most precious period instruments in the world.