I recently visited the exhibition of Cezanne's portraits at one of my favourite places in London, The National Portrait Gallery. Now, I was taught to remember 'there are no lines in nature' which isn't a bad rule for someone like me to make sure a painting from life is, well, lifelike as far as possible. Cezanne must have missed that lesson and I was struck by how the strong outlines in his portraits do have a kind of cartoon quality but then, being well off, Cezanne  didn't need to make a living from his art. So, maybe the magical simplicity that makes his work so identifiable and appealing comes from the fact that he painted mostly for his own enjoyment and could afford to ignore all the rules - or could be he was just a genius for whom rules don't apply.