In Thomas More’s hugely influential Utopia, a traveller recounts his discovery of an island nation in which the inhabitants enjoy unprecedented social cohesion and justice. The book imagines a community in which laws, personal relations and professional ambition are based on reason, in contrast with the tradition-bound superstitions of Europe, which were, in More’s eyes, impediments to equality and peaceful coexistence.One of the indicators of the profound cultural and political influence of More’s masterpiece is today’s common use of the word "Utopia" – a term he invented. This extraordinary treatise on the values of rationality and reason – here presented in a sparkling new translation by Roger Clarke and accompanied by copious notes and additional texts – questions what a philosopher can do to enact change in society, and how idealized visions can inform political practice.