Music operates as a motif in Portrait. First, Henry James uses music to suggest transitory states and the process of change. Most significantly, Isabel meets Madame Merle while the latter is playing the piano. Isabel hears the music first, and recognizes that it is Schubert, being played with care and feeling. The fact that Madame Merle is in the house when Isabel inherits the fortune is the catalyst for the rest of the plot of the novel and Isabel’s disastrous marriage. Madame Merle’s early comment about music similarly foreshadows the later events of Isabel’s life: “[T]here are moments in life when even Schubert has nothing to say to us. We must admit, however, that they are our worst” (180). Ralph advises Isabel not to “question [her] conscience so much—it will get out of tune like a strummed piano” (227). 

Music is also used as a metaphor for aspects of character. James addresses the similarities and differences of Ralph and Gilbert in a passage that uses music as a metaphor. After referencing the sense of taste and “appearance of thinking that life was a matter of connoisseurship” (265), Isabel reflects that this aspect of character is an anomaly for Ralph, but “in Mr Osmond it was the keynote, and everything was in harmony with it” (265).