How we work: Pablo Picasso, artist

Picasso made Gertrude Stein sit more than 80 times for a portrait in 1906 (during which they would discuss Cezanne). Then: "Spring was coming and the sittings were coming to an end. All of a sudden ... Picasso painted out the whole head. I can't see you any longer when I look, he said irritably. And so the picture was left like that" [Stein, The Autobiography of Alice B. Toklas]

On his return from three months' travel, Picasso repainted the head without having seen her again. She said: "I was and still am satisfied with my portrait, for me, it is I, and it is the only reproduction of me which is always I, for me."

When someone commented that Stein did not look like her portrait, Picasso replied, "She will."