Although the theological elements of Robert Boyle’s mechanical philosophy have received careful scrutiny, his reflections on economic issues have largely been overlooked. This article takes a small step towards redressing this state of affairs. Rather than argue that Boyle – like John Locke or David Hume – was as interested in political economy as he was in discovering the nature of Nature, the article treats him as a point of entry for considering how early-modern England negotiated the revolutionary cultural and (...) economic changes that emerged as capitalism took command. More specifically, it uses one of Boyle’s less-famous inventions – a hydrostatic device for discriminating between real, degraded and counterfeit coinage – in order to explore how economic exchange began to acquire a patina of ‘objectivity’ in the 17th-century imagination. (shrink)