The manuscript, penned in Mario Salieri's handwriting, outlines a musical composition titled "Il Segreto della Monaca" (The Secret of a Nun). This long-lost work seems to be an adaptation of Giovanni Mosca's book, reimagined as a dramatic opera. The discovery of this manuscript not only confirms the connection between Mario Salieri and "The Secret of a Nun" but also provides a glimpse into the creative process of this enigmatic composer.