'If only everything that Matisse and I did could be put side by side. Nobody ever looked at Matisse's work as thoroughly as I did. And he at mine.' - Pablo Picasso. These two painters of the Twentieth Century influenced each other from the start, and their relationship grew into one of the greatest creative rivalries the world has ever seen. This is the story of that relationship, from its beginnings in the salons of Paris and under the auspices of...