While some seventeenth-century scholars promoted natural history as the basis of natural philosophy, they continued to debate how it should be written, about what and by whom. This look into the studios of two Amsterdam physicians, Jan Swammerdam (1637–80) and Steven Blankaart (1650–1705), explores natural history as a project in the making during the second half of the seventeenth century. Swammerdam and Blankaart approached natural history very differently, with different objectives, and relying on different traditions of handling specimens and organizing (...) knowledge on paper, especially with regard to the way that individual observations might be generalized. These traditions varied from collating individual dissections into histories, writing both general and particular histories of plants and animals, collecting medical observations and applying inductive reasoning. Swammerdam identified the essential changes that insects underwent during their life cycle, described four orders based on these ‘general characteristics’ and presented his findings in specific histories that exemplified the ‘general rule’ of each order. Blankaart looked to the collective observations of amateurs to support his reputation as a man of medicine, but this was not supposed to lead to any kind of generalization. Their work alerts us to the variety of observational practices that were available to them, and with what purposes they made these their own. (shrink)