Auguste Rodin, who lived from 1840 to 1917 and was hailed as the founder of modern sculpture, argued that “the only principle in art is to copy what you see.” Jean Hans Arp, who lived from 1886 to 1966 and was a founding member of Dadaism, said, “A painting or sculpture not modeled on any real object is every bit as concrete.” While Rodin created turbulently expressive human forms in bronze and marble, Arp created sleekly biomorphic abstract paintings and sculptures. In one of the Beyeler’s largest-ever sculpture exhibitions, 110 works bring these two monumental artists face to face, revealing their differences, but also unexpected affinities and shared references. —E.C.