RESUMEN: Leopold Kozeluch (1747-1818), the most influential of the many Bohemian musicians then working in Vienna, was by the end of the 18th century "the most celebrated composer in all of musical Europe"- more admired than Mozart and Haydn, and this despite his refusal to perform in public. Credited with inspiring the "vogue of the fortepiano", his 50 solo keyboard sonatas represented the final stand against the impending division between professional and amateur music-making. Although their "pure" and "pleasing" qualities fell out of fashion amidst the musical agitations of tha 19th century, they are "classics" in the truie sense of the word, recoghized by late 18th-century theorists as perfect models of the genre. They are also fundamental to improving an understanding of the general musical landscape of the Classical period so often distroted by a focus on great masters to whom Kozeluch is inevitably considered to be " subsidiary" , a dismissal which has allowed his innovations- the cantabile idiom, and the tragic- pathetic manner inherited by Schubert and Beethoven- to be overlooked. In this article a thorough survey of Kozeluch´s keyboard sonatas, and of contemporary responses to them makes it possible to appreciate a composer who held firm to an aesthetic increasingly abandoned by successors whose assessment remain largely unchallenged, and to share in Susan Burney´s "gratification of finding Kozeluch triumphant over all prejudices".