This essay develops a new perspective on the scientific imagination in seventeenth-century England by attending to one of its wayward expositors, the poet Andrew Marvell. His famously difficult country-house poem, "Upon Appleton House" (1651), makes the unfamiliar suggestion that “carelessness” intensifies receptivity to natural (and other) phenomena. No extant interpretive rubric (sprezzatura, say, or “repression”) captures the genuine freedom from exertion Marvell asks us to discern in his speaker’s signature affect. The poet’s casual indifference casts a new light on the history of experimentalism extending from Francis Bacon to Robert Hooke and beyond.