Why did Georges Braque stencil letters into The Portuguese?

Georges Braque stenciled letters into his 1911 painting The Portuguese as part of the Cubists' experimental investigation into the nature of reality and representation in art.12

By incorporating real-world elements like stenciled lettering, Braque and his collaborator Pablo Picasso sought to move away from traditional illusionistic painting, which aimed to create the appearance of depth and space. The inclusion of lettering served several key purposes:23

• Defining the Picture Plane: The letters emphasized the two-dimensional surface of the canvas, suggesting that the image should be read as coming forward from the plane rather than receding into a traditional perspectival space.3
• Autonomous Reality: This technique, along with the later use of collage, helped establish the idea that a painting is an autonomous object rather than a mere imitation of the world.12
• Compositional Elements: Lettering functioned as a flat pictorial element that played off other shapes and motifs within the composition, helping to denote objects rather than depict them through traditional illusion.23

This practice was a hallmark of Analytical Cubism, where the artists analyzed the intrinsic character of their subjects through fragmented forms and signs.23