jats:titleAbstract</jats:title> jats:pThe intellectual career of William Stukeley (1687–1765) has received much attention. However, one manuscript by Stukeley has never been discussed. In 1757 he composed a short treatise, ‘On the Philosophy of Pleasure’, in which he argued an unusual case, namely, that a man and woman ought to feel entitled to consummate their philosophic friendship with kissing. The manuscript illuminates an interesting episode in Stukeley’s private life, but it also has a broader significance. Firstly, it incorporates many of the themes developed elsewhere by Stukeley, showing how contemporary historical and scientific understanding could be synthesised with a mystical account, of ancient derivation, of the physical and social universe. Secondly, the manuscript sheds light on the changing relations of men and women. Social and cultural developments among the literate in eighteenth-century Britain were facilitating heterosocial interaction, outside the framework of courtship and marriage, in ways that enhanced both the possibilities for heterosocial friendship and the risks attached to it. In his manuscript, Stukeley sought to expand the physical expression of amicable affection between a woman and man: he was looking for ways to move beyond the constraints of Platonic love without falling into libertinism. His position accords with the idea that the pursuit of happiness in the eighteenth century had a sexual dimension. However, while Stukeley sought greater latitude in erotic expression, his effort illustrates the challenge of doing so without undermining the contemporary norms of social order.</jats:p>