The English painter David Hockney has been keeping diaries filled with snapshots since 1967. In this film Hockney explains that the photos are more than mere chronicles of his friends and travels; they provide the compositional elements on which his paintings and graphic works are based. For example, photographs of castles he took during a boat trip down the Rhine were later adapted for a suite of etchings to accompany six Grimm's fairy tales. Going through his photo diaries, Hockney reveals projects to come, those that might be and those that will never be. Most important, the motivation and eye behind his unique style of realism becomes apparent. He’s seen at work on a large canvas of his friends Celia and Ossie Clark and their cat Percy, commissioned by the Tate Gallery.