Alexander Calder was a 20th-century American abstract artist who pioneered “mobiles”: sculptures suspended from string that moved according to wind and touch—just like those hanging above infants’ cribs. Calder integrated chance into his sculptures, partially removing the artist’s agency. The whimsy of the colorful, suspended, irregular shapes that make up a Calder work is only amplified by the subtle rotations and bounces inevitable in their display. Calder is less remembered but still revered for his just as endearing, bright, two-dimensional work, as well as his large stationary sculptures.