One of the central drivers of love in Passion is beauty. The idea that beauty is power verbalizes one of the central themes of show, though Fosca has learned that her lack of beauty can also be turned into a kind of power as well. Clara's beauty clearly played a part in Giorgio's love for her; Giorgio tells Clara she's beautiful so many times throughout the show that we start to wonder if that's all he loves about her. How differently Giorgio would feel about Fosca if she were beautiful, and she knows it. Meanwhile, Clara is worried that when she gets old and is no longer beautiful, Giorgio will no longer love her (and she might be right). The Count says to Fosca in the flashback that he gave her his looks, the privilege of being married to a handsome man, in exchange for Fosca's money. He knows the value of physical beauty and he knows how to use it to his advantage, just as Fosca later learns to use her ugliness to her advantage. On the other hand, using that beauty has its consequences; as the doctor says, beauty is something we must pay for.
Sondheim deftly shows us that Fosca learned to manipulate people by watching the Count manipulate her. We find out that many of the things Fosca says to Giorgio during their first meeting are actually things the Count once said to Fosca. She has learned his tricks and even stolen actual lines from him. Is this revenge against the world, or men, in general? Or was this an education in survival the count unwittingly gave her? Is this what she really got for her parents' money? Fosca uses almost exactly the same words to Giorgio that the count used to her. She is imitating the Count's seduction very closely. Since she has ascertained that she and Giorgio are very much alike, she figures he will fall for the same lines she did. But Fosca has moved up in the world. In the flashback, she is the victim and she is passive. But she goes from being the object, being watched, in the flashback to being the viewer in the present, from being acted upon in the past to be the one acting upon others in the present. She is in control now.
Sondheim has frequently used the image of a social outcast observing life from a window, as in "Finishing the Hat" in Sunday in the Park with George, and the image of seeing someone else framed or imprisoned in a window, as Anthony sees Johanna in Sweeney Todd. The window also represents passivity. Fosca is first observed by the count as he passes by and she sits in her window. Later, Fosca observes Giorgio while he's walking and talking and she sits in her window. She is passive, watching as the world goes by without her. She is not a participant, only an observer, yet she does learn from her observations, as we see in her adoption of the count's methods.
In any other musical, the flashback would seem like a mini-opera, almost continuous music with important leitmotifs (musical phrases that represent a character or idea) that are repeated and developed throughout. But the entire score of Passion is structured that way, the flashback just fits neatly into the fabric of the piece as a whole. Musical ideas from earlier in the score are developed here, and musical ideas introduced here will be further developed later in the show. In addition to the musical artistry here, the textual information is incredibly important, offering us vital information about Fosca's past, her past and present mental state, and the things that drive the actions of both Fosca and the colonel.
The flashback starts with a brisk waltz tempo, the style that has been established as the conversation music of Passion, in this case, it's the spoken conversation of the colonel and the written conversation of Fosca, both directed at Giorgio. Inside this waltz rhythm are numerous musical figures based on Fosca's "I Read" accompaniment and other music we've heard earlier in the show. When the colonel introduces Count Ludovic to his aunt and uncle, we hear the music that has been Fosca's piano theme up until this point. We will find by the end of the flashback that this theme was the Count's theme first, then after he destroyed Fosca's life, it became her theme, a theme of love lost, of emotional destruction, and of obsession. This is the music she hears when she first meets him and it is music she will always associate with him and with the pain he caused her. We learned early in the show that Fosca plays this theme at the piano; she relives this moment, meeting the Count, over and over. The pain -- and the music that describes it -- has become a part of her, shaping her personality, her view of the world and of love.
The Count begins his seduction of Fosca ("I've seen you at your window") and immediately we recognize this music. It's the same music -- and almost the same lyric -- that Fosca used when she first met Giorgio. Fosca learned to manipulate, to seduce, from the Count. Of course, without physical beauty, she had to adapt his strategy (which is why her lyrics to Giorgio are close, but not exactly the same) to suit her own talents. In the second section of the flashback, we hear Fosca's danger motif, the one we hear just before bad things have happened elsewhere in the show, this time just before Fosca finds out the Count is a fake and a con man. The melody to the mistress' lines, telling Fosca the Count is a fake, is a variant of Fosca's "I Read" theme, her main theme. Again, this information, this episode have shaped who she is, so the theme has stayed with her, become part of her. By using this musical theme, Sondheim reinforces the idea that this moment becomes an integral part of Fosca's shattered mental state. This is why Fosca must escape reality, as she explains in "I Read," why she does not search for truth.
In the third section of the flashback, the Count's farewell song contains one section with an accompaniment reminiscent of Fosca's "I Read" accompaniment, and one section in a peppy waltz tempo -- music that trips happily along as the Count tells Fosca he's destroyed her life, he's leaving her, and the rent is overdue. In the final section of the flashback, the underscoring begins by quoting Fosca's father's earlier line, "A woman's like a flower" as the Colonel continues the story. Here, Fosca re-quotes her father's words. In her mind, she is like a flower, therefore, her only purpose is to please, and she has failed to please the Count. She has failed at being a woman. Meanwhile, the Colonel is telling us that this was when Fosca became ill for the first time -- we discover that her sickness is directly linked to the Count, to her heartbreak and her conviction that she is a failure as a woman (which of course is only being reinforced in the present by Giorgio's rejection). Beauty is power, therefore she has no power. Longing is a disease, therefore her longing, her feeling unloved, becomes a literal, physical disease.
The colonel sings a section blaming himself for not knowing the Count was a con man, to the music of Fosca's "I Read" motif. We discover that Fosca's entire past, everything that created the sick, bitter creature she has become, is all tied up in the one little melodic motif from "I Read." In fact, the colonel's melody to the words, "Why could I not admit the truth," is the same music to which Fosca sang "I do not read to search for truth." Everyone in this family has trouble with facing the truth. We find that "I Read," the song that describes her philosophy of life was born out of the cruelty of her past. The next section of the flashback, "The enemy was love," starts with another melodic quote from "I Read,", then continues with a melody that always accompanies discussions of the definition of love throughout the show. Giorgio will use this melody later when he tells Fosca what love ought to be, and again when he tells Clara what love ought to be. It's interesting to note that when the Colonel says that "the enemy was love," he corrects himself; it was really selfishness more than it was love, he says, yet another fascinating connection to Fosca's present behavior. The colonel knows that his happiness for Fosca was partly the relief in being rid of her, and he assumes her parents felt the same way. Yet Fosca's willingness to ignore the danger signals was motivated by selfishness as well -- she wanted a man in her life, no matter what the consequence might be -- so should the Colonel really feel guilty about what happened? Finally, all the major players in the flashback (except Fosca) come together to restate the central musical and textual idea of the scene, indeed the central idea of the entire show: "Beauty is power, longing a disease."