Jacob and Picasso shared a room, a bed and a hat, one working by day, the other by night. Apollinaire, Salmon and Cocteau were among his neighbours and friends at the Bateau Lavoir. Braque and he invented cubism, Gonzalez helped him with his sculpture, and Leiris and Stein wrote about him. Proust, Joyce, Diaghilev and he dined with Stravinsky after the première of ‘Renard.’ He collaborated with Satie, Diaghilev, Massine, Cocteau and de Falla on seminal dance pieces. Maar was his lover and photographed the painting of Guernica; Brassaï was a friend for decades, Picasso saying that his photos explained him best.