Artists are transformers. Neither the identity of alchemist nor the identity of artist was, during Wijck's lifetime, a completely circumscribed point. Alchemy's hybridity and mutability often found it passing within, and across, the boundaries of countless other disciplines. By contrast, artists appear to provide a much simpler categorization, an identity fortified by guild memberships and fees and stylistic genealogies. Yet artists, too, worked to stretch and redefine the borders of their creative territory: they worked as anatomists and naturalists, producing objects that straddled curious beauty and scientific document; they rejected the familiar, if unglamourous, model of the craftsman for the quixotic and dangerous possibilities of the genius; they worked as theorists and critics and picture dealers and artistic hagiographers, actively revising the canon even in the midst of its emergence. Drebbel, the pupil of Goltzius, successfully trained as a painter and engraver before turning to work as an engineer, a chemist, and an inventor of curiosities. Phillips Angel, whose encomium to the painters of Leiden continues to shape our ideas of Golden Age artistry, set aside his practice to become a buyer for the Dutch East India Company, yet later served as painter and drawing master for the Shah of Persia. Art acted as commodity, as diplomatic currency, as decoration, as moral exemplar, as conversation piece, as record, as challenge, as vision or dream. Artists’ roles could be no less fluid, no less protean or adaptable, than the objects they produced.

I noted at the beginning of this book that alchemy often appears as a stand-in for mystery. But Wijck's pictures resist these interpretations by their emphatic materiality, or else they reimagine it by relocating the true repository of natural secrets in the painter's art, rather than in the alchemist’s. As James Elkins writes, “Painting is alchemy. Its materials are worked without knowledge of their properties […] a painter knows what to do by the tug of the brush.” Alchemy, in other words, did not have to school Wijck in the fundamentals of material change. He was primed to see its lessons clearly by the lens of his own training.