Series in which mathematician Marcus du Sautoy explores the stories behind some of the world's most familiar scientific diagrams.

What exactly is light? What is colour? In the mid-1660s, Isaac Newton bought a pair of prisms at a fair near Cambridge, which were to be the basis of a series of experiments that would unlock a secret that had occupied scientists for centuries - the nature of light itself.

To explain what he had done, Newton created a diagram. It is called The Crucial Experiment and is a pivotal image in scientific history, a graphic moment when the ancient world was overturned by modern science. Newton demonstrated that white light is not pure, but made up of a number of different colours, the colours of the rainbow.

Newton's ideas transformed our knowledge of what we see and how we see, and the prism and its refracted colours became a captivating image. From fibre optics to the cover of Pink Floyd's album Dark Side of the Moon, Newton's work went on to influence centuries of science and art. Show less