Cogito ergo sum notwithstanding, what else do you know about the 17th-century Frenchman regarded as the father of modern philosophy? The good thing about Naxos’s series of introductions to philosophers, which includes Plato, Aristotle and Nietzsche, is the way it gently guides you through what could be some pretty daunting theories of belief or, in Descartes’ case, doubt. Every excerpt from the original text is preceded by a brief explanation. Here, for example, is the intro to his Principles of Philosophy published in Latin in 1644: ‘Principles is divided into four parts covering metaphysics, physics, cosmology and geology, each with a number of titled paragraphs. In the preface Descartes describes his view of human knowledge using a tree as a metaphor. The branches are the applied sciences such as medicine, psychology, mechanics and even ethics. The trunk of physics supports these, and all are nourished by metaphysics or philosophy at the root.’ René Descartes (1596-1650) was Renaissance man epitomised – a brilliant polymath interested in so many different disciplines (the cartesian coordinates system is still used in maths) that, to give himself time and space to think, he abandoned Paris and spent nine years travelling, occasionally as a mercenary, throughout Europe. His lifelong habit of rising late began as a child, when he was sent away to a Jesuit school and managed to convince his teachers that his poor health required him to stay in bed for most of the morning. 50 years on he accepted a position at the Swedish court to teach philosophy to Queen Christina whose only free time, it turned out, was at 5am. Unused to chilly dawns, Descartes caught pneumonia and died, aged 53.