Born in Philadelphia to a celebrated family of classical statuary sculptors, Alexander Calder utilized his unique innovative genius to profoundly change the course of modern art.He is perhaps best known for his invention of the mobile, a word coined by Marcel Duchamp to designate Calder's kinetic arrangements of flat, brightly colored abstract forms hung from thin wire trusses.These mobiles respond to the subtle interactions of air currents, and thus, constantly change within the flux of motion.

The mobile, however, marks only one of Calder's achievements. In his later stabiles, static sculptures in painted sheet metal, Calder created innovative works by exploring the aesthetic possibilities of untraditional materials.As the mobiles did before them, the stabiles proposed a new definition of abstract sculpture based on the ideas of openness and transparency, challenging the prevailing notion of sculpture as a composition of mass and volume.

Throughout Calder's career, which spanned much of the twentieth century, he merged stabiles and mobiles in a number of formats. Calder’s further experimentation with scale in the 1960s and 70s created a new era of public sculpture; this is evidenced by the fact that many of his monumental stabiles have become civic landmarks and grace museum sculpture gardens around the globe.