Part four of Oprah’s discussion with Pulitzer Prize-winning writer Isabel Wilkerson and readers of the book, Caste: The Origins of our Discontents. The fourth episode in the eight-part series focuses on the fourth pillar of Caste, “Purity Versus Pollution.” Isabel explains how the caste system keeps groups separate for the protection of the “purity” of the dominant caste against the pollution of the “subordinate” caste. Oprah, Isabel and guests talk about the heartbreaking story of Al Bright, a nine year old Black child who was shamed when barred from sharing a pool with his little league baseball teammates 1951. We’ll hear from one of Al’s best friends who knew him at the time of the incident.