In the photograph within Leslie Hewitt’s photograph Make It Plain, 2002–2005, two worn paperbacks, both published in 1968, sit on a tabletop. One is the Kerner Commission’s report on the race riots of the year before, the other Joanne Grant’s historical study Black Protest. At once elegiac and enigmatic, Hewitt’s work implicitly asks the question at the heart of curator Jeffrey Grove’s exhibition “After 1968”: What do the 1960s mean— what can they mean—to African-American artists too young to have experienced the social upheaval of those times directly but who know the era through books, family