Picasso: Challenging the PastThis catalogue of the exhibition at London's National Gallery is generously illustrated, and includes intelligently written and informative essays concerning particular periods in Picasso's working life. I was especially pleased to see that some of the old master works which Picasso worked from are illustrated alongside his version of the painting - for example Velazquez's Las Meninas, paired with one of Picasso's versions of the picture, or, Delacroix's Women of Algiers and Picasso's response to the subject. Well worth having as a way of enhancing enjoyment of the exhibition.