Niall Ferguson is the preeminent historian of the ideas that define our time. He has challenged how we think about money, power, civilisation and empires. Now he wants to reimagine history itself.

In October 2017, Ferguson came to the Intelligence Squared stage to unveil his new book, 'The Square and The Tower'. Historians have always focused on hierarchies, he argues – on the elites that wield power. Economists have concentrated on the marketplace – on the economic forces that shape change. These twin structures are symbolised for Ferguson by Siena's market square, and its civic tower looming above. But beneath both square and tower runs something more deeply significant: the hidden networks of relationships, ideas and influence.

Networks are the key to history. The greatest innovators have been 'superhubs' of connections. The most powerful states, empires and companies have been those with the most densely networked structures. And the most transformative ideas – from the printing presses that launched the Reformation to the Freemasonry that inspired the American Revolution – have gone viral precisely because of the networks within which they spread.