From the beginning of his musical career, Giuseppe Verdi tried to develop opera beyond the structures, rules and dramatic traditions that had bound it for so long. But he had to be careful about any experimentation: opera audiences were notoriously conservative and came to the theatre expecting certain conventions, certain ways of communicating sung drama. A scena or 'scene' had to be built in a certain way, an aria had to have a specific form, heroines were almost always lyric or coloratura sopranos, villains' roles were always performed by basses, heroes were always tenors, etc. One flaunted or experimented with these conventions only at great risk to one's career in the theatre since the audience could always be counted on to 'vote with it's feet' and repay the upstart composer by staying away from his operas.
Verdi's early operas, then, were very much in the mold of the Italian bel canto school at least in terms of sheer structure. Musically speaking even early critics of the composer could tell that this composer was something apart from the standard lyrical output of his contemporaries. But as early as Ernani (1844) he began to experiment with the use of the baritone voice-type (a voice-type not generally recognized up to this point in Italian opera) to communicate a character with far more complex motives than the usual bass-villain, a character far more dynamic and dramatically mercurial than audiences were used to seeing onstage. As the years and the operas went by, Verdi's baritone characters became more interesting, more real; in a word, more human, paralleling Verdi's consistent attempt to make opera itself less artificial and more naturalistic.
Along with the development of the baritone came the development of a musical style that was more natural as well, necessitating a move away from the ossified forms and conservative structures of the past. This development was more or less applied to all elements of the opera including all voice-types (soprano, mezzo-soprano, tenor, baritone and bass) by the composer, depending entirely on the specific dramatic demands of the libretto. And the greatest amount of experimentation in musical characterization can be found in the brilliant middle-period operas La traviata, Il trovatore and Rigoletto, and it is in the latter that we see (and hear!) some exciting new developments.
After the atmospheric prelude or short musical introduction to the opera (does any other composer do so much to establish an emotional environment with so few notes?), we hear party music dance music that is seemingly banal and lacking in subtlety. It could not be more different from the music of the prelude and is almost shocking in its context. And it is certainly not what a mid-nineteenth century audience member should have expected at the beginning of a tragic opera. But Verdi's intention is crystal-clear: he wants us to immediately realize the salacious and libidinous nature of the Duke's court with music as raw and unrefined as the court and its ruler. Rather than have the singers act out the intended seediness (something that would have been impossible in Verdi's day), the composer leads the audience's imagination into creating the appropriate atmosphere by composing music highly suggestive of an amoral gathering of aristocratic party-goers. Overlaying this realistic party music are the first utterances of the singers, a ribald conversation between the Duke and Borsa, one of his courtiers, about the Duke's latest conquests. This kind of conversation would normally have been treated (certainly by any number of other Italian composers of Verdi's time) by more traditional recitative. But Verdi couches the conversation in the context of stage music accompanied, under normal circumstances, by a small band of instrumentalists in the wings or behind the scenery. In this way the composer gives the impression of a real party going on in real time before our very eyes. Verdi's nineteenth century audience, then, became part of the scene and was brought much closer to the stage events. And what better way to create a sense of ducal moral decay than to create music that one could characterize as being as tacky as the court itself? The transition from the dance music to the first number accompanied by the pit orchestra occurs seamlessly as the violins enter in leaping octaves at the start of Questa o quella, the tenor's first aria.
These first three or four minutes of Rigoletto may not seem so unusual to us now, predisposed as we are to hear this familiar music after some 150 years of acquaintance with it. But compare it with some of the more sublime moments from this score (the Rigoletto/Gilda duet from Act II or the famous Act IV quartet, Bella figlia) and we get the point rather quickly: this score is far from uneven, Verdi is simply casting his music to perfectly fit the dramatic situation.
Let's go a bit farther in trying to understand Verdi's musical characterization. Notice that the tenor's solo music is almost all of an assertive, blatantly tuneful nature. Questa o quella, Parmi veder le lagrime and La donna è mobile are all carefully calculated to communicate the character of the Duke, whom we know to be a shallow, vain man whose main interest is not so much involved with statecraft as it is in plotting his next amorous conquest. We also know that his Renaissance court is absolutist; he is a dictator entrenched in the old monarchical system whose courtiers and subjects are under his complete and direct authority. These kinds of political systems are, by nature, highly conservative. It should not surprise us that, although Rigoletto is a very experimental opera for Verdi, there are older, more traditional operatic forms still present: they are to be found in the music of the Duke, or in music with which he is involved. The Duke has, for instance, the only double-aria (Act II's Parmi veder le lagrime being the slow cavatina, and Possente amor the requisite cabaletta) and the only strophic arias (Questa o quella and La donna è mobile) in the entire score. The Duke's duet with Gilda in Act I is also much more reflective of older operatic treatment, with its slow movement (È il sol dell'anima) and consequent cabaletta-like fast movement (Addio, addio, speranza ed anima).
But the real experiment operatically, dramatically and musically is to be found in the character of Rigoletto himself. The jester at the center of Victor Hugo's play Le roi s'amuse was just the complicated, unusual and grotesque character that Verdi was looking for at the time. With a character produced from a fermentation of distrust, trickery, paranoia and paternal love, Verdi had a creation ripe for the new kind of opera that he desired above all to create. One only need listen to Rigoletto's Act I monologue "Pari siamo" to realize that we are in a completely revolutionary operatic world. It is not of the ordered, contained world of the traditional aria, and yet it is not strictly recitative either. Verdi has created a hybrid form, closely akin to the Shakespeare soliloquy in traditional theatre, which gives the character of Rigoletto ample dramatic space to communicate the emotions roiling within him. Notice there is no 'tune' in Pari siamo. We have instead musical gestures, short powerful motives that stop, start, trail off and sometimes (but only sometimes!) sing, acting in real time much the same way the human mind acts in real life. Verdi hinted at this kind of revolutionary musical structure in his early Shakespeare opera, Macbeth, but in this present piece he surpasses all other creations before it. To the mind of a typical nineteenth century aficionado, Rigoletto's first solo utterance must have seemed very strange indeed, as he would surely have expected at this moment a double-aria or even a pure recitative leading us into the duet with his daughter. Rigoletto's character is treated similarly throughout the entire work. Consequently, with all his flaws, he comes across as one of the most human characters in all nineteenth century Italian opera.