Science has fundamentally changed the way we view the universe. It has replaced angels, demons, gods and miracles with force, energy and natural selection. It has been a battle to uncover the simple rules that govern the universe in the face of opposition from the most powerful institutions in history. And it wouldn’t have happened without one a fourteenth-century monk who called the Pope a heretic.This is the story of William of Ockham, his life, his ideas and his influence, but it is also the story of science itself, the battle between complexity and simplicity and the long shadow of a tool known as Occam’s Razor. In this magisterial book, Johnjoe McFadden takes us from the riverbanks of Ancient Babylonia to inside the Large Hadron Collider and shows us how the modern world wouldn’t be possible without a little-known monk from Surrey.