When I first read W.E.B. Du Bois’ 1903 book, “The Souls of Black Folks,” some 90 years after it was published, I was struck not only by its enduring relevance but also by the searching poetry with which it explored truths about racial identity in America. The central passage, now among the most famous in literature, bears quoting in full:“It is a peculiar sensation, this double consciousness, this sense of always looking at one’s felt self through the eyes of others, of measuring one’s soul by the tape of a world that looks on in amused contempt and pity. One...