From the 1920s to the 1940s, the theme of a bird in flight preoccupied Brancusi. He concentrated on the animals’ movement, rather than their physical attributes. In Bird in Space, the sculptor eliminated wings and feathers, elongated the swell of the body, and reduced the head and beak to a slanted oval plane. Balanced on a slender conical footing, the figure’s upward thrust appears unfettered.