To mark the 50th anniversary of Picasso's death, the Musée du Luxembourg is staging a major exhibition on the story of the extraordinary friendship between two 20th-century icons, Pablo Picasso and Gertrude Stein. Gertrude Stein, a Jewish-American immigrant, writer, poet and aesthete, moved to Paris in 1903, shortly after the arrival of Picasso, then a young artist. Their position as foreigners and their marginality underpinned their membership of the Parisian bohemian scene and their artistic freedom. Their friendship crystallized around their respective work, which founded cubism and the pictorial and literary avant-gardes of the 20th century, and their posterity is immense.