[…] Among the initiatives you have planned, I think particularly of the international conference to mark the centenary of the outbreak of the First World War. In it you will review research’s most recent findings, paying special attention to the Holy See’s diplomatic initiatives during the tragic conflict and the contribution Catholics and other Christians made by coming to the aid of the wounded, refugees, orphans and widows, by searching for the missing, as well as by rebuilding a world torn apart by what Benedict XV termed “needless carnage” (Letter to Leaders of the Peoples at War, 1 August 1917). And the heartfelt appeal of Pius XII still resonates today as timely as ever: “Nothing is lost by peace. Everything may be lost by war” (Radio message: Un’ora grave to the Heads of State and peoples of the world, 24 August 1939). When we listen again to these prophetic words, truly we realize that history is the “magistra vitae”. […]