 More read Descartes’s Principia philosophiae in 1646, and it had a very profound effect upon him and upon the subsequent development of his own philosophy. “All that have attempted anything in naturall Philosophy hitherto are mere shrimps and fumblers in comparison of him”, More wrote in 1648 (Letter to Hartlib, 11 December 1648, Webster 1969, 365). Accordingly, he began to teach Descartes’s mechanical philosophy to interested students in Cambridge, and so became one of the earliest conduits for the dissemination of Cartesianism in Britain. More is credited with inventing the word, Cartesianism, and has been said to be behind the strangely Platonic reading of Descartes’s methodology in the anonymous preface to the first English translation of the Discourse of a Method (1649) (Cristofolini 1974). In his later writings, however, More is much more critical of this new philosophy. It used to be assumed that More began as a follower of Descartes and became more critical of his philosophy as his own philosophy matured. It is now recognised, however, that More was always critical of certain aspects of Cartesianism, and that the increasingly negative attitude towards Cartesianism reflects a growing realisation that Descartes’s errors (as More saw them) were not simply infelicities, which might be corrected by philosophical negotiation, but were defining characteristics of Cartesianism, particularly as the philosophy was developed by his followers, after Descartes’s own untimely death (Gabbey 1982, 1990; Reid 2012, 2018; Leech 2013).