The discovery of a small collection of Darwin manuscripts at the Whipple Museum of the History of Science has allowed a reconsideration of Darwin’s interest in and knowledge of microscopy. Concentrating on the years between his return from the Beagle voyage and the publication of the major taxonomic work on barnacles, this paper recovers a number of important aspects of Darwin’s intellectual and practical development: on returning from the Beagle voyage he acquainted himself with the work of C. G. Ehrenberg, (...) and this informed both his private and public work; then through the 1840s Darwin transformed himself from a fascinated observer and consumer of others’ work into an expert on microscopy. I characterise this move as a piece of clever manoeuvring, and discuss more generally the kind of scientist—gentlemanly and expert—that Darwin was attempting to become.Keywords: Charles Darwin; Microscopy; Beagle voyage; Classification; Accuracy. (shrink)