What is rhetoric? Is it the capacity to persuade? Or is it 'mere' rhetoric: the ability to get others to do what the speaker wants, regardless of what they want? This is the rhetoric of ideological manipulation and political seduction. Rhetoric is for some a distinctive mode of communication; for others, whenever someone speaks, rhetoric is present. This book is devoted to helping readers understand these rival accounts, by showing how it has happened that there are so many conceptions of rhetoric. Any such approach must be rooted in classical antiquity, since our ideas of rhetoric are the product of a complicated historical process starting in ancient Greece. Greek rhetoric was born in bitter controversy. The figure of Gorgias is at the centre of that debate and of this book: he invites us to confront the terrifying, exhilarating possibility that persuasion is just power.