The exact sciences have an immense weight and influence in our culture. At the heart of their effectiveness lies the mathematical equation. The difficult form of the great equations - particularly those of modern physics - has often acted as an obstacle to any understanding and they have come to embody the mystery and terror of modern science. This volume brings together some living scientists, historians and writers about science. They each seek to unpack an equation so that it becomes understandable. The contributors include Roger Penrose, John Maynard Smith, Arthur Miller, Steven Weinberg and Oliver Morton.