In 1911, Sonia Delaunay made a patchwork quilt for Charles's crib, which is now in the collection of the Musée National d'Art Moderne in Paris. This quilt was created spontaneously and uses geometry and colour.
"About 1911 I had the idea of making for my son, who had just been born, a blanket composed of bits of fabric like those I had seen in the houses of Ukrainian peasants. When it was finished, the arrangement of the pieces of material seemed to me to evoke cubist conceptions and we then tried to apply the same process to other objects and paintings." Sonia Delaunay[9]
Contemporary art critics recognize this as the point where she moved away from perspective and naturalism in her art. Around the same time, cubist works were being shown in Paris and Robert had been studying the colour theories of Michel Eugène Chevreul; they called their experiments with colour in art and design simultanéisme. Simultaneous design occurs when one design, when placed next to another, affects both; this is similar to the theory of colours (Pointillism, as used by e.g. Georges Seurat) in which primary colour dots placed next to each other are "mixed" by the eye and affect each other. Sonia's first large-scale painting in this style was Bal Bullier (1912–13), a painting known for both its use of colour and movement.