Poetry is a beautiful way of spoiling prose, and the laborious art of exchanging plain sense for harmony.

Walpole’s quip treats “poetry” less as an elevated mode than as a kind of deliberate distortion: it “spoils” prose by prioritizing sound-patterns and ornament over straightforward statement. The phrase “laborious art” underscores that versifying is work—craft, not inspiration alone—yet the work is framed skeptically as an “exchange” in which clarity (“plain sense”) is traded away for euphony (“harmony”). Read in context of Walpole’s famously witty, epistolary style and his Enlightenment taste for lucidity, the remark can be taken as a satirical defense of plain speech, while also acknowledging poetry’s technical discipline and its power to transform meaning through form.