Alexander Calder introduced kinetic motion to sculpture in 1931 with his celebrated "mobiles"—a term coined by Marcel Duchamp. Comprising arced wire armatures and hand-cut sheet metal forms painted in black, white, and primary colors, these hanging structures are defined almost entirely by movement: gyrating, swaying, expanding, and contracting in myriad unpredictable configurations, their shadows dancing across the surrounding walls.

Calder mounted his first postwar exhibition at Galerie Louis Carré, Paris, in October 1946, for which Jean-Paul Sartre wrote a celebrated catalogue essay defining the mobile as "a little local fiesta; an object defined by its movement and non-existent without it." Untitled (circa 1946), exemplifies the mobile as Calder reinvented it upon his triumphant return to Paris after the war. Unfolding across two tiers—a red wire armature above suspending a black blade, red disc, and white panel; a branching black wire structure below animating orange and black triangles and a bold yellow circle—the work deploys an almost complete lexicon of the artist's vocabulary of forms, their interplay of color and motion embodying all the dynamism and wit of his postwar achievement.