An essential and timely book, restoring Pacem in terris to its full prophetic force in our troubled time. Massimo Faggioli writes with historical clarity and genuine passion, showing how John XXIII’s insightthat peace rests on truth, justice, and freedomremains decisive today; not a nostalgic memory, but a compass in an age of chaos, when even wars seem to have lost strategy and measure. In conversation with the teaching of Pope Francis and Pope Leo XIV, these pages reveal that peace is not an abstract idea but a historical and spiritual task that calls the global conscience, as international law fractures and war reemerges as the language of politics. A book that reopens the future just when it seems to be closing.Massimo Faggioli