Based on the Book of Jeremiah, Verdi's "Nabucco" treats its source quite freely, adding nearly all the characters and changing the ending. The opera was one of Verdi's earliest unqualified popular successes, and has stayed in the repertory to the present day. Many of the principal roles are dramatic and truly virtuosic: the role of Abigaille, in particular, has long been considered one of the most challenging (even dangerous) roles in all of opera. Nevertheless, the chorus is the true hero of the opera. The Italian public loved "Va Pensiero," in which oppressed Israelites dream of regaining their sovereign homeland, and this chorus quickly became a popular hit, overshadowing the title character Nabucco, known in English as Nebuchadnezzar, the proud Babylonian king who first loses and then regains his sanity.