“She is establishing a different voice,” said the Liberian poet Patricia Jabbeh Wesley. “She is not writing about the war, she is not writing about poverty or writing about villages in a patronizing way.” This is a comment on the Liberian-American writer Wayétu Moore and her 2018 novel, She Would Be King. But it applies as well to Lina Iris Viktor, a British-Liberian artist. Her paintings in “Dark Matter,” rendered in radiant ebonies and midnight blues, punctuated or symbolically patterned with 24-karat gold, boldly position “the black figure,” writes the show’s curator, Renée Mussai, “as the universal human form.” —J.V.