sentences:  Christoph Wolff, in a 2012 book entitled "Mozart at the Gateway to his Fortune", disputes the view that Mozart's last years represented a steady slide to despair and the grave; he also disagrees with interpretations of the music as reflecting late-life despair (for example) "the hauntingly beautiful autumnal world of [Mozart's] music written in 1791".An early rumor addressing the cause of Mozart's death was that he was poisoned by his colleague Antonio Salieri.This rumor, however, was not proven to be true as the signs of illness Mozart displayed did not indicate poisoning.