The Roman Catholic priest and philosopher Thomas White (1592/3–1676), known as ‘Blacklo’, was born into a recusant family, educated at the colleges of St Omer, Valladolid, Seville, Louvain and Douai, and spent some of his adult life in Paris, where he knew the mathematician Marin Mersenne and the astronomer Pierre Gassendi. Later, in London, he moved among pioneering natural scientists and was a member of the intellectual circle from which, after the Restoration, emerged the Royal Society. White was the author of two notable works of natural philosophy, which attempted to synthesise traditional Aristotelian views with the new Copernican cosmology and the revived atomic theory of Epicurus. To White, atomism provided a scientific explanation of transubstantiation. His philosophical publications were praised by both Descartes and Hobbes, but he was also the leader of the controversial group of English Catholics known as Blackloists, who were willing to accommodate themselves to the new Cromwellian state in order to achieve religious toleration. In 1655 White published his remarkable treatise The grounds of obedience and government, which opened with the Ciceronian motto ‘Salus populi, suprema lex esto’ and a dedication to his long-standing friend and fellow-philosopher, the recusant Sir Kenelm Digby. With its explicit acknowledgment of a social contract, the book was widely seen as offering recognition to Cromwell's Protectorate: ‘The title of the magistrate begins and dies with the good of the commonwealth, and holdeth purely so long as it is good for the people.’ Most commonly described as wholly secular in tone, to Stefania Tutino the text instead reflects the belief that God governs men by granting them free will and rationality. Her book claims to provide the first full study of White and his circle, but much of it relies heavily on the pioneering work of Beverley Southgate, who first brought the Blackloists to the attention of scholars. It is also poorly proof-read, with historical errors – for example Digby is given the non-existent title of ‘Gentleman of the Privy Council’, instead of Privy Chamber – and contains numerous ungrammatical or unintelligible sentences apparently transcribed directly from notes. The publisher should have ensured a higher standard of professional copy-editing. Nevertheless, the book is valuable for providing in an appendix the full text of White's treatise, with helpful footnotes adding important historical and philosophical information together with bibliographical cross-references. Thomas White and the Blackloists deserve to be much more generally known, since in recent years his treatise has emerged as one of the most striking arguments for religious liberty put forward in the seventeenth century.