He said that such steady pulses reminded him of soldiers marching or horses trotting, sounds no longer heard in the late 20th century, and he wanted his music to capture the sort of continuous acceleration or deceleration experienced in an automobile or an airplane. While Carter's music shows little trace of American popular music or jazz, his vocal music has demonstrated strong ties to contemporary American poetry. He set poems by Elizabeth Bishop ("A Mirror on Which to Dwell"), John Ashbery ("Syringa" and "Mad Regales"), Robert Lowell ("In Sleep, in Thunder"), William Carlos Williams ("Of Rewaking"), Wallace Stevens ("In the Distances of Sleep" and "The American Sublime"), Ezra Pound ("On Conversing with Paradise"), and Marianne Moore ("What Are Years"). Twentieth-century poets also inspired several of his large instrumental works, such as the "Concerto for Orchestra" (St. John Perse) and "A Symphony of Three Orchestras" (Hart Crane).