‘Subtle thresholds’ was a project specifically concerned with how the epistemological constructions of ‘difference’ and ‘analogy’ have been used to mediate the cultural understanding of pathology. In an attempt to communicate bodies of knowledge, the bio-medical and biological sciences have often had to rely on analogy to carry complex ideas, and it is these persuasive visual analogies that occupy a central role in the formation of public perception. Disease has been visualised as a state of difference – another category of existence. It is imagined as a space of separation, both physical and psychological, whereby the patient becomes identified through and by their disease, or what Sander Gilman refers to as the fixity of disease as a constant other.

Infectious disease, however, offers a meeting point between species. Disease is not something discrete and of itself, but dependent on a relationship between a host and an organism in order to exist – evidence of an ongoing relationship of inter-speciation. Situated in the gallery between social history and natural history displays, the exhibition aimed to create a conceptual bridge between the two areas, making use of collections from the Iziko South African Museum and the Adler Medical Museum at Wits. It referenced plague-altars, zoonotics, pharmacopoeias, ‘sites’ of contamination and bestiaries, and presented an exploded view of science – suggesting interconnectivity between organisms, world-views, science and mythologies. The manner in which bio-medical and biological science is visually expressed is often linear and non-layered. This project borrowed from those languages, but, by using various curatorial strategies in a lattice of conceptual and visual cross-referencing, attempted to express information in a manner that allowed for a layered reading of the inter-relationships of species.