Calder asked Duchamp, "What should I call these things. " Duchamp replied, "Mobiles, " this was a French pun, which meant motive and motion. Jean Paul Sartre described the mobile as, " The mobile is a little private celebration, an object defined by its movement and having no other existence. A mobile does not suggest anything. It captures genuine living movements. Mobiles have no meaning, they are, that is all. " In Calder's early years as an artist, it seems he was systematic in his approach to "composing motions." Later, having perfected his technical methods, he became ever more inventive with his moving sculpture. The most engaging aspect of Calder's sculpture was its interaction with space. Mobiles participated in lively dialogues with their environs, reacting to air currents and human touch. The stabiles enfolded and incorporated spatial volume. As Calder put it: "I paint with shapes."
During this time, Calder fell under the spell of Leger, Duchamp, Arp, Klee, and Picasso. His greatest influence however was Miro who was a direct inspiration for many of the shapes that he used. Miroís biomorphic motif survived in Calder's art until the end of his life. Calderís sculpture was the perfect marriage of abstraction and movement. Einstein once visited a Calder show and stood transfixed for forty minutes in front of a work called Universe. By 1937, Calder was thinking of making monumental public sculptures of his works. He refused to call his work art, "I call them objects, that way no one can come along and say, these arenít sculptures, it washes my hands of having to define them."