The American artist Alexander Calder (1898-1976) was born in Philadelphia to a family of sculptors. Before attending the Art Students Leave in New York to study painting from 1923-1926, Calder studied engineering. In the mid 1920s he began to mould circus characters from wire and wood. In 1931, after moving to Paris, he was associated with Joan Miró and joined the abstraction-Creation movement. Duchamp, seeing Calder’s sculptures at the time, called them “mobiles” because of their kinetic ability. Calder challenged the definition of sculpture with these dynamic, light works that defied the typical static, monumental associations of the medium. Nevertheless, Calder continued to work with stationary sculpture also, giving them the term “stabiles” as suggested by Jean Arp. He is most famous for the colourful mobiles he created after returning to the United States in 1933, which were set in motion by air movement and resemble constellations of petal-like forms. At the Venice Biennale of 1952 he won the main prize for sculpture.