He was the patriarch of Modernism. But have we become so familiar with Cézanne's ground-breaking vision that we have forgotten how anxiously hard-fought it was in the making? This son of a banker, born in Aix-en-Provence in 1839, was still in his early twenties when he abandoned his law studies and set out on the artistic course that was to change the entire way that we portray our world. “Cézanne is the father of us all,” as Pablo Picasso said. A new exhibition sets out to rinse a dried crust of art history from the surface of some our nation's most significant paintings. This week, as the finale of its 75th birthday celebrations, the Courtauld Institute pulls its entire Cézanne stock out of the cupboard and displays them together for the first time.