7/31/1492. In cities, towns and villages across late medieval Spain, whole districts have emptied out. Houses abandoned, stores closed, and synagogues—which until recently had been alive with singing and prayer—now sit quiet. Exactly four months earlier, the King and Queen of Spain issued an edict: by royal decree, all Jewish people in Spain must convert to Catholicism or leave the country, for good. Why were the Jews expelled from Spain? How did Spaniards, and then the world, start to think of religion as something inherited, not just by tradition, but by blood? And how does this moment help us understand the challenge of assimilation today?

Thank you to our guest, Professor Jonathan Ray from Georgetown University and author of "After Expulsion: 1492 and the Making of Sephardic Jewry" (2013).