“I think I have spoken enough to you about serious things,” Sophie Taeuber-Arp, a pioneer of Dadaism and the first wife of Jean Arp, once said, “which is why I speak [now] of something to which I attribute great value, still too little appreciated—gaiety.” This comment comes as no surprise, considering that Taeuber-Arp had been a dancer, choreographer, and puppeteer. Constructivist, Dada, concrete, abstract—all these words apply to her diverse practice in one way or another, yet Taeuber-Arp had none of the cynicism or anger that characterized fellow radicals. Her blocks and blobs of color are lyrical, joyful—a visual expression of the energy coursing within. This is Taeuber-Arp’s first-ever U.K. retrospective. —E.C.