The art historian Leo Steinberg (1920-2011) was known for defying orthodoxy, most memorably in his 1983 book The Sexuality of Christ in Renaissance Art and in Modern Oblivion, in which he argued that the genitals depicted in images of the infant Jesus and the Passion were crucial to establishing the saviour’s essential humanity. The book ruffled feathers: some found the topic prurient, while others challenged Steinberg’s interpretation of the visual evidence. But most were struck by the incisiveness of his conversational voice, which he had already wielded in essays and criticism about artists including Pablo Picasso and Jasper Johns.