For twenty years, Robert Prevost lived and worked in Peru. Now, as Pope Leo, he is going back, and the journey carries a weight that few papal trips can claim. It begins a twelve-day tour of three South American countries, and it is the first time he has travelled to the region since undergoing surgery for lung cancer. The itinerary is as revealing as the medical history.

Uruguay, Argentina and Peru differ sharply in how they relate to the Church. Uruguay is among the most secular societies in Latin America, where public life has long kept religion at arm's length. Argentina, the homeland of the late Pope Francis, remains deeply marked by his legacy and by the expectations that came with the first Latin American pontiff. Peru, by contrast, is personal: it is where Leo served as a missionary and later as a bishop, and where he may be welcomed less as a distant figure than as a familiar one.

The tour also tests a question that hangs over every modern papacy: how much can an ageing leader of 1.4 billion Catholics do in person? Long-haul travel is physically demanding, and a schedule that spans several countries in under two weeks will be watched closely for signs of strain. Supporters will argue that visible presence is itself the message, particularly in a region where Catholicism is competing with fast-growing evangelical churches and rising indifference.

Whether the trip reassures the faithful or simply raises new concerns about stamina may become clear only as the days pass.