Collaborations with Boito in the revision of the 1857 opera "Simon Boccanegra" helped to convince Verdi of Boito's ability as a librettist. Musicologist Roger Parker speculates that Verdi's final agreement to revise "Boccanegra" was based on a desire to "test the possibility" of working with Boito before possibly embarking on the larger project. Frank Walker expresses much the same thoughts, noting that "some of the results, such as the magnificent scene in the Council Chamber and the villainous Paolo's Iago-like recitatives, foreshadow the later opera."