Among Verdi's operas Stiffelio, which immediately preceded Rigoletto and was first staged in Trieste in 1850, is in several respects unusual, and in one, unique. To take the last first: Unique, because the only one of Verdi's operas whose orchestral score, in main part, was lost for almost a hundred years, during which time the opera could not be staged or even studied with any assurance that the reader was in touch with what Verdi intended. For its initial decade, however, it had existed in a severely censored form, had played in several theaters, and from that period some vocal scores, librettos, and reviews had come down, enough to give a good idea of how very unusual an opera it was for its day.

Unusual, in that its leading tenor is not a young lover but a middle-aged, married, Protestant minister. Unusual, in that it and Traviata are the only operas Verdi conceived to be played in contemporary dress, and unusual because between Nabucco and Falstaff it is the only opera in which he musically declared the ending happy. And most unusual in its steady focus on a tenet of religious belief, the Christian dogma of forgiveness for sin: how it might be practiced or ignored.

Like most composers, Verdi often had put the Church onstage in choir or procession, massed voices, bells, and colorful cardinals, but in Stiffelio he took this core belief of Christianity and portrayed the psychological difficulties of a nineteenth-century Protestant pastor, who discovers his wife has been unfaithful: Can he practice what he preaches? Can he forgive her, both as a minister of God and as a husband?

No opera of the time displayed so bluntly the contrast, some might say the hypocrisy, of professed belief and accepted human behavior. Moreover, in Catholic countries priests do not marry, and in the operatic world, adultery was avenged not by divorce, as Stiffelio offers his wife, but by killing the third party and often the wayward spouse. Even before the premiere in Trieste, religious censors wrote out all references to God, to the Bible, and to the protagonist's role as pastor, so that the minister of God, instead of preaching to his congregation about Jesus forgiving the adulterous woman, became merely a layman speaking to a group of like-minded people about the merits of forgiveness as a general policy.