The theory of memetic evolution--explaining the reproduction of cultural units called "memes"--illuminates the decline of poetry as a cultural presence by clarifying the contrasting attitudes towards poetry manifested by the co-discoverers of natural selection: Charles Darwin and Alfred Wallace. Darwin's eventual indifference to poetry can be traced to an all-absorbing faith in science that extinguishes poetry-favouring memes (such as religious beliefs, memories of the "useless" past and reflections on inexplicable mysteries). In contrast, Wallace's abiding passion for poetry reflects a surprising insistence on the limits of science, an insistence that protects poetry-sustaining memes.