Most of us give little thought to the back of the book - it's just where you go to look things up. But as Dennis Duncan reveals in this delightful and witty history, hiding in plain sight is an unlikely realm of ambition and obsession, sparring and politicking, pleasure and play. In the pages of the index, we might find "Butchers, to be avoided", or "Cows that shite Fire", or even catch "Calvin in his chamber with a Nonne". Here, for the first time, is the secret world of the index: an unsung but extraordinary everyday tool, with an illustrious but little-known past.

Charting its curious path from the monasteries and universities of 13th-century Europe to Silicon Valley in the 21st, Duncan uncovers how it has saved heretics from the stake, kept politicians from high office, and made us all into the people we are today. We follow it through German print shops and Enlightenment coffee houses, novelists' living rooms and university laboratories, encountering emperors and popes, philosophers and prime ministers, poets, librarians and-of course-indexers along the way. Revealing its vast role in our evolving literary and intellectual culture, Duncan shows that, for all our anxieties about the Age of Search, we are all index-rakers at heart - and we have been for 800 years.