This book is about the key ideas of the great eighteenth-century philosopher Jean-Jacques Rousseau. Born in Geneva in 1712, he died at Ermenonville (then just outside Paris but now virtually a suburb) in 1778. Most famous nowadays for his contributions to social and political theory, with The Social Contract of 1762, an essay on the fundamental questions of social justice and political legitimacy, being his best-known work in this area and probably overall, he also wrote a best-selling novel, Julie, or The New Héloïse (1761); a very important book on educational theory though with a wider intent, Émile, or On Education (1762); an extraordinarily original and influential autobiography, The Confessions, written between 1764-1770 and published posthumously; other works of selfinterpretation and self-defence; essays on language and musical theory, a dictionary of music and a successful opera; works on botany, and a host of other things. This prodigious and wideranging output earned him an enormous if controversial reputation at the time, and many of his ideas have continued to have a powerful impact ever since.