Mirror to the Sky — Mark S. Geston

Secretive, enigmatic beings, they came to Earth to live among humanity in quiet, aristocratic isolation. But now, after years of silence, the "gods" have decided to share their art.

Across the vast galactic void come great ships bearing the fruits of an incomprehensible alien culture - paintings and sculpture of such raw, visceral power that their unveiling plunges the Earth into violent chaos, and sends the visitors fleeing from their adopted planet. But some remain behind - to face death at the hands of rampaging mobs, to witness the outcome of the grand cosmic game, and to assist in the creation of one last, potentially universe-shattering masterpiece that will illuminate the awesome, final destinies of god and man.