Though the poem does not adhere to any conventional poetic form like a sonnet or a villanelle, it does possess a certain form. First of all, the opening stanzas are written in an uneven but effectively droll tetrameter. The lines do not intentionally rhyme, though an occasional end-rhyme sneaks into the poem. However, the steady rhythm of the first four stanzas is radically interrupted by the intrusion of outside voices, the shouts of the railway porters. Here, the lines become jagged and fragmentary, so that the narrative that was originally fairly symmetrical has now become asymmetrical. In keeping with the symphonic metaphor suggested by the title, the poem moves from harmony to discord, from consonance to dissonance. In poetic terms, the poem shifts from monologue to dialogue. The singular lyric voice has to give way to a collage of other voices, all of whom are competing for...