The University of California at Berkeley commissioned American neoclassical composer Roger Sessions (1896–1985) to set the poem as a cantata to commemorate their centennial anniversary in 1964. Sessions did not finish composing the work until the 1970s, dedicating it to the memories of civil rights movement leader Martin Luther King Jr. and political figure Robert F. Kennedy, who were assassinated within weeks of each other in 1968. Sessions first became acquainted with "Leaves of Grass" in 1921 and began setting the poem as a reaction to the death of his friend, George Bartlett, although none of the sketches from that early attempt survive. He returned to the text almost fifty years later, composing a work scored for soprano, contralto, and baritone soloists, mixed chorus and orchestra. The music is described as responding "wonderfully both to the Biblical majesty and musical fluidity of Whitman's poetry, and here to, in the evocation of the gray-brown bird singing from the swamp and of the over-mastering scent of the lilacs, he gives us one of the century's great love letters to Nature."