In the novel Northanger Abbey, Jane Austen writes of the “advantages of natural folly in a beautiful girl.” The conceptual artist Mark Dion has made it his mission to set forth the advantages of folly in art. A new exhibition places 13 of Dion’s “follies”—sheds and other structures inviting visitors to look inside, where varying scenes promote Dion’s signature exploration of nature, culture, and art—amongst the sprawling greenery of the Storm King Art center. —J.V.