This book brings together 11 pairs of opposing speeches on foreign policy written by Florentine statesman and historian Francesco Guicciardini (1483-1540), freshly translated with new commentary. Collectively, they constitute a remarkable collection of debates on war, peace, alliance and more. Incisive and elegant, the debates contain an early formulation of concepts such as the balance of power and the security dilemma - ideas that are still in international politics today. This book highlights the importance of Guicciardini's work for the evolution of international theory and explains why he, alongside Machiavelli, should be considered a leading figure of Realism.