Gold has forever been an object of fascination. The stuff of beauty, vanity, and greed, of princes and pirates, it symbolizes light, but unleashes dark forces. It is used to create objects of spirituality and worship. It has also shaped cruel power struggles. In “Gold and Magic,” treasures from the National Museum of Denmark are placed in conversation with works by contemporary artists such as Marina Abramovic, El Anatsui, Ugo Rondinone, and Ai Weiwei. —E.C.