Thucydides famously declared his work to be 'a possession for all time', and so it has proved to be, as each age and generation has seen new things to admire in it and take from it. In the last hundred years, Thucydides has been interpreted and invoked in support of many different positions in politics, political theory and international relations. Geoffrey Hawthorn offers a new and highly original reading, one that sees him as neither simply an ancestor nor a colleague but as an unsurpassed guide to a deeper realism about politics. In this account, Thucydides emerges as sensitive to the non-rational and the limits of human agency, sceptical about political speech, resistant to easy generalisations or theoretical reductions, and opposed to any practical, moral or constitutional closure in politics. The book will be of interest to students of politics and classics.