Recently, my five-year-old asked, “What is an ancestor?” This triggered a crisis of middle-aged forgetting. I have no memory of not knowing about slavery, so how little could I possibly have been when I learned not only that chattel slavery had once existed in the Americas, but that the cockamamie-sounding truth had to do with me? “Your ancestors were stolen from their homes, taken across the Atlantic Ocean, and sold as things,” I will tell my son soon.

So when I climbed the ramp of the African American Museum in Philadelphia to see “In Conversation: Visual Meditations on Black Masculinity,” I