Contributed by Margaret McCann /Amy Sherald’s paintings of mostly ordinary and upright African Americans, in “American Sublime” at the Whitney Museum, transcend portraiture, vaulting to socio-political metaphor. Their evocative titles – drawn from Emily Dickinson, Zora Neale Hurston, Toni Morrison, and other cultural figures – suggest an array of personalities or experiences. But the exhibition title, from Elizabeth Alexander’s poem of the same title, unsettles our understanding of what both figures and viewers behold.