Explore the complex world of debt, default, and forgiveness in this second part of the 2017 Ulam Lectures series delivered by John Geanakoplos at the Santa Fe Institute. Delve into the leverage cycle and its role in explaining major financial crises, including the 2007-2008 mortgage debt crisis, the European debt problem, and the looming student debt issue. Examine the mathematics behind debt crises, the challenges of debt forgiveness, and the importance of appropriate debt relief. Gain insights from Geanakoplos, a distinguished economist and financial expert, as he discusses housing prices, interest rates, financial innovation, credit surfaces, and policy responses to debt crises. Learn about his advocacy efforts and analysis of the Greek crisis, providing a comprehensive understanding of the intricate relationship between debt and economic stability.