'Most rare workmen': optical practitioners in early seventeenth-century Delft

A special interest in optics among various seventeenth-century painters living in the Dutch city of Delft has intrigued historians, including art historians, for a long time. Equally, the impressive career of the Delft microscopist Antoni van Leeuwenhoek has been studied by many historians of science. However, it has never been investigated who, at that time, had access to the mathematical and optical knowledge necessary for the impressive achievements of these Delft practitioners. We have tried to gain insight into Delft as a 'node' of optical knowledge by following the careers of three minor local figures in early seventeenth-century Delft. We argue that through their work, products, discussions in the vernacular and exchange of skills, rather than via learned publications, these practitioners constituted a foundation on which the later scientific and artistic achievements of other Delft citizens were built. Our Delft case demonstrates that these practitioners were not simple and isolated craftsmen; rather they were crucial components in a network of scholars, savants, painters and rich virtuosi. Decades before Vermeer made his masterworks, or Van Leeuwenhoek started his famous microscopic investigations, the intellectual atmosphere and artisanal knowledge in this city centred on optical topics.