Born in 1898 in Philadelphia, Alexander Calder was the son of a well-known sculptor. From 1915 to 1919, he studied mechanical engineering at the Stevens Institute of Technology. His interest in drawing and sculpture came from his observations of machines and mechanical objects. In 1923, he enrolled at the Art Students League in New York. His passion for drawing led him to produce an important number of sketches, depicting people in the underground as well as the Barnum and Bailey Circus. From these sketches he created his famous ‘Cirque Calder’, a wire sculpture representing a miniature circus, which enabled him to be recognised and become close to the Parisian avant-garde. In 1930, he met Mondrian, who had a decisive impact on his work: Calder stopped producing naturalist compositions in order to embrace abstract art (“du Mondrian qui bouge”). Calder’s sculptures, which Duchamp called “mobiles”, were designed with delicately balanced or suspended components that altogether created a dynamic harmony. He exhibited them for the first time in 1933. The same year, he established a studio in Roxbury, Connecticut. Since then, he spent his time between France and the United-States. In 1936, he was one of the few American artists to participate in the ‘Cubist and Abstract Art’ exhibition. As from 1943, he produced stationary sculptures called ‘stabiles’, which later took monumental proportions. Alongside his sculptures, Calder did not stop painting and drawing colourful and poetic compositions. He produced works in which primary colours contrasted with his usual black shapes.