Calder is best known for his development of sculptures in motion, known as "mobiles." A second major mode in his work was the "stabile," a stable sculpture that rests on the ground. The sculptor Jean Arp, whose biomorphic vocabulary influenced Calder, coined the term stabile in order to contrast them to Calder's mobiles. Calder's first large stabiles date from the mid-1930s but it was not until the late 1950s and 1960s that they began to attain the colossal scale of MIT's La Grande Voile (The Big Sail). In such works, Calder wanted to achieve a massiveness of form and scale without sacrificing the lightness and sense of motion of his mobiles. The stabiles establish as few points of contact with the ground as possible. The subtle interplays between straight and sinuous edges and between flat and curved planes and the appendages jutting out from the framework communicate an epic quality and a soaring dynamism. The large stabiles provide changing experiences of space as the spectator moves around and through them. Sudden angles and planes slice, divide, and mold the space into varied shapes. Calder wrote: When I use two or more sheets of metal cut into shapes and mounted at angles to each other, I feel that there is a solid form, perhaps concave, perhaps convex, filling the dihedral angles between them. I do not have a definite idea of what this would be like, I merely sense it and occupy myself with the shapes one actually sees. Calder's forms are imaginatively derived from nature, and their presence is strongly organic. Such stabiles as La Grande Voile suggest primeval beings, giant insects or birds raised up on their legs and spreading their wings in an impressive array of spars, blades, bolts, and rivets. The spirit of play is powerful in everything that Calder made, as is his sense of joyful and ebullient invention. Calder's working method involved making a small model that was then mathematically enlarged and fabricated in large scale under his supervision at an
