A photograph by Zanele Muholi sets up a triangular relationship between skin colour, race and identity (plate 1). The artist, who identifies as non-binary, stares out at the viewer: a visual activist challenging their spectator. A white stripe painted down Muholi's nose calls for comparison with Matisse's portrait of his wife with a green stripe down hers (plate 2), such that Muholi not only reworks the image of a woman objectified by a man, but critiques one of the canonical figures of the Western tradition, celebrated for his non-representational colour. When developing this photograph, Muholi brought up the contrast with the effect that highlights approach pure white and the deeper tones, especially that of their skin, are deepened, blackened. Muholi makes skin colour, then, especially binary colour difference, the issue at stake. Skin colour plays a key role in defining identity for them, in a country (South Africa) in which it is explicitly racialized and where it once defined a system of extreme racism, whose legacy is still keenly felt. Skin colour, here, is a determining characteristic of race. Its ability to give rise to meaning, to identity and to prejudice is inseparable from gender and other issues with which it intersects, such as social class. The contrast of black and white signals difference.The purpose of this article is to examine skin colour in a place and at a time different from Muholi's and to question whether that triangular set of associations, which are so pertinent to our time, were equally present. 1 Fra Angelico's Miracle of the Black Leg, painted before 1443 in Florence, provides a compelling case study (plate 3), both because the arresting combination of a black and a white leg on a single individual cannot but prompt a consideration of skin colour, but also because it was painted before the first west African slaves arrived in Europe through the activities of Portuguese traders. Interpretation of this imagery requires the art historian to ask about contingency in the perception of skin colour: what associations did black skin colour carry for the entirely white audience of Fra Angelico's panel and how was it inflected by their religion, by Christianity?My focus on skin colour, rather than on the larger category of race, requires justification. Scholars have been engaged by questions of race in premodernity since the 1980s, especially in literary studies, but the last decade or so has witnessed a marked shift in scholarship over whether race was operative in premodern European societies. 2 The issue hinges on definition and periodization, as well as on distinctions between histories of race and of racism. 3 It also depends on whether race is approached as a 'period' idea or as a conceptual framework for critical analysis. On one side of the argument are those who argue that ideas of difference and ethnicity in premodern