In this fascinating conversation with Carnegie Council President Joel Rosenthal, historian Ted Widmer looks back on 13 pivotal days in Abraham Lincoln's life in 1861--the basis for his new book "Lincoln on the Verge." How would American and world history be different without Lincoln's ethical leadership? And as the U.S. struggles through the COVID-19 pandemic, what can the Civil War era teach us about political divisiveness in 2020?