It was by a roundabout route that the autograph score of Haydn’s most important piano work ended up in the New York Library via a collector. Its four leaves contain a fair copy of the work- two leaves with a sketch-like character follow. Haydn composed the work, at the time still entitled ''Sonate'', for ''Signora de Ployer'' (probably the pianist Barbara Ployer associated with Mozart). The variation movement was apparently intended as the beginning of a sonata with several movements. As can be