Called ‘the most noted person of his age’ by Anthony Wood, Henry Stubbe (1632-76), classicist, polemicist, physician, philosopher and the most important critic of the early Royal Society, has never had a biography. This study seeks to fill that gap, while standing received opinion about him on its head. The older view has it that at the Restoration Stubbe renounced his radical past and became the enemy of scientific progress and a reactionary defender of church and monarchy. Professor Jacob shows instead that Stubbe continued to espouse radical views after 1660 by devious means. Publicly he resorted to a rhetoric of subterfuge, while he let the full extent of his radicalism be known in private conversations at Bath and in an important clandestine manuscript (which Jacob proves to be his) that circulated among radicals from the early 1670s well into the eighteenth century.