Charles Rosen Quote
It is typical of Schumann's musical thinking to construct this complex network of references outside his music-to quote Beethoven, and then to have Beethoven's distant beloved refer to Clara. But this should give a clue to the nature of Schumann's achievement. It is not Schumann's music that, refers to Clara but Beethoven's melody, the "secret tone."
Ch. 2 : Fragments - The Romantic Generation (1995)