(Note: This show first aired earlier this year.) The acclaimed journalist and bestselling author Daniel Okrent is our guest; he tells us about his book, "The Guarded Gate: Bigotry, Eugenics, and the Law That Kept Two Generations of Jews, Italians, and Other European Immigrants Out of America." This book looks back to the 1920s is reveal a dark, forgotten chapter of American history -- a troubling era with serious implications for the present day. "The Guarded Gate" tells the story of the scientists who argued that certain nationalities were inherently inferior, thus providing the intellectual justification for the harshest immigration law in American history. Brandished by various upper class Bostonians and New Yorkers -- many of them (surprisingly) progressives -- who led the anti-immigration movement, these eugenic (and pseudo-scientific) arguments helped keep hundreds of thousands of Jews, Italians, and other unwanted groups out of the U.S. for 40+ years.