Jacob Viner and Bertil Ohlin were among the preeminent scholars of international economics. From their early careers in the 1920s and 30s they were also interlocutors and friends. Their unpublished correspondence reveals much about the development of Ohlin’s thinking about capital flows and German reparations, including in the famous 1929 “German Transfer Problem” debate with J. M. Keynes. Ohlin’s analysis and position in that debate emerged from a longer-running debate with Viner. The correspondence also reveals how they weighed the values of scholarly criticism, personal loyalty, and acceptance of revealed truths that challenge past beliefs.