A Calder mobile sways, hesitates. One might say that it makes some mistake and then starts over again. Once in his studio I saw a mallet and a gong hung from the ceiling. At the slightest gust, the mallet would chase the spinning gong. Like an awkward hand it would attack, throwing itself forward, only to veer off to the side. Then, just when one least expected it, it would bang the gong squarely in the center with a terrible noise. A mobile’s motions, on the other hand, are ordered with so much art that one could never classify them with the marble rolling on an uneven surface where all direction comes from the accident of the terrain. Mobiles have lives of their own. One day when I was talking to Calder in his studio, a mobile which had been at rest became violently agitated and came at me. I stepped backwards and thought I was out of reach. But suddenly when this violent agitation had gone, and the mobile seemed to have recoiled into rest, its long majestic tail, which had not yet moved, lazily, almost reluctantly came to life. It turned in the air, and then swung right under my nose. These hesitations, renewals, gropings, blunders, brusque decisions, and, above all, this marvelous swan-like nobility make Calder’s mobiles strange creatures existing between matter and life. Sometimes their motions seem motivated, sometimes they seem to have lost their ideas in the midst of their actions and become bewildered—bouncing like idiots. Like a swan, like a frigate, my bird flies, swims, floats. He is one, one specific bird. Then, all of a sudden, he breaks apart and there is nothing left but metal stems filled with ineffectual little quivers. These mobiles have been made neither wholly living nor wholly mechanical, they fly apart at every instant, and yet they always return to their initial position. When they are caught in the rising air they are like aquatic vegetation swayed by the current, like petals of the sensitive plant, like legs of a frog when the brain has been removed. Although Calder has tried to imitate nothing—he has wanted to create only scales and harmonies of unknown motions—his works are both lyrical inventions and almost mathematical, technical combinations. They are symbols of nature—that great vague nature which wastes pollen or which suddenly produces the flight of a thousand butterflies, that unknown nature which might be a blind chain of cause and effect or a timid development, always delayed, always disturbed, inspired by an Idea. This article was originally published, on the occasion of Alexander Calder’s recent Paris show, by Louis Carré whose permission to publish this translation we wish to acknowledge.
Keter-class Objects are broadly defined as "inimical threats to all of humanity", and are listed along with Humanoids and Jokes as concepts that are difficult to write because the process of coming up with something that is broad-reaching enough to threaten all of humanity while allowing the Foundation to maintain the veil of secrecy and being an interesting read is surprisingly difficult. While a planet-sized monster that can swallow the earth in one gulp might certainly be classified as a Keter-class entity, it would be almost impossible to write it in such a way as to be plausible (within the Foundation's literary framework) and interesting.