Didactic poetry has fallen firmly out of favour as a contemporary genre: it is a literary form rarely used by modern authors and seldom read by the twenty-first-century public. A remark in Shelley’s preface to Prometheus Unbound (1820) offers one enduring explanation for its demise: ‘Didactic poetry is my abhorrence; nothing can be equally well expressed in prose that is not tedious and supererogatory in verse.’ Why write in verse, the argument runs, if one aims at clarity and pedagogical precision; conversely, why aim to communicate factual information if one values sublimity and the poetic imagination? A technical manual in verse fits the perceived role of neither poetry nor prose.