‘Zeno's tortoise’ examines Zeno's best-loved paradox, Achilles and the tortoise. Zeno's great innovation, for which he is justly famous, lies in how he persuades us to accept unwelcome revisions to our standard beliefs. ‘Zeno's paradoxes’, as we generally call them, are vivid pieces of thought-experiment which work by setting up a scenario that seems familiar, only to show that things cannot possibly happen as we generally believe them to happen. Zeno pushed the analysis of reality onto a new plane. The topics he grappled with belong to what we call metaphysics, and his puzzles enter territory that is still fought over.