The Beauty of Diagrams

In the last hundred years, one diagrammatic image stands above all others. It represents a scientific breakthrough that has been voted the most significant in the 20th century, more important than penicillin or the first working computer. The double helix shows us what the structure of our DNA looks like. Francis Crick and James Watson announced their discovery in Nature magazine in April 1953, and their article included a diagram of the structure by Odile Crick. The image she drew has become so well known and loved that we now find it in a whole range of consumer products - there are double helix ties, dogs chews and even a perfume. So has the image of the double helix become so divorced from its original scientific setting that no one knows what it really is or what it stands for?

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 Dark Side of the Moon album, Newton's work went on to influence centuries of science and art.

He looks at Leonardo da Vinci's world-famous diagram of the perfect human body, which has many layers from anatomy to architecture, and defines our species like no other drawing before or since. The Vitruvian Man, drawn in the 1480s when he was living and working in Milan, has become one of the most famous images in the world. Leonardo's drawings form a vast body of work, covering every imaginable subject in spectacular detail: from feet, skulls and hands to muscles and sinews; from hearts and lungs to buildings, bridges and flying machines. Vitruvian Man perfectly synthesises Leonardo's passions for anatomy, for the mechanics of the human body and for geometry. It is also full of surprises, illustrating an ancient architectural riddle set out 1,500 years earlier by the classical writer Vitruvius about the relative proportions of buildings and men; a riddle that, even today, still fascinates and beguiles experts and viewers alike.