Roni Horn's midcareer survey at the Tate Modern takes a while to warm up to, but give it some time and the shimmering, meditative work will begin to invite you in. The 54-year-old New York artist’s first solo show in Britain, the exhibition encompasses the full range of her diverse career—from refulgent glass sculptures to drawings, photography, and text-based pieces—and introduces viewers to her recurring themes of identity, androgyny, and water.