The torrid history of two nations and the travails of a Church overcoming the loss of its leader loom large over Pope Benedict's four-day visit to Poland. As a German who was enrolled in the Hitler Youth and conscripted into the army that invaded Poland in 1939, he will carry the burden of a bloody past on his journey of reconciliation. Though he took no part in fighting and deserted the army, there will be powerful symbolism for Poles in seeing Pope Benedict tour Warsaw, a city levelled by the Nazis, and visit Auschwitz, the acme of Adolf Hitler's vast killing machine.
Though trifling beside the Nazi invasion of 1939 and Prussia's role in helping partition Poland three times in the 18th century, another row is now straining ties between Germany and Poland. Poland's defence minister has recalled the Molotov-Ribbentrop pact, which divided Poland between Hitler's Germany and Josef Stalin's Soviet Union, to describe how Warsaw feels about plans for a huge pipeline taking gas from Russia to Germany but bypassing Poland.
After a gradual warming of ties with Berlin, Poles felt betrayed that a fellow member of the European Union and Nato had struck a secret deal with a Moscow that they deeply mistrust. And with the perceived injury came the insult of former German chancellor Gerhard Schröder, whom Poles saw as an ally, accepting a job as chairman of the pipeline project, which is a joint venture with Russia's state-owned energy giant Gazprom, a firm controlled by the Kremlin of Mr Schröder's friend, Vladimir Putin.
At a time when the EU is questioning Russia about its reliability as an energy supplier and its willingness to use its oil and gas reserves as political weapons against its neighbours, Poland had hoped for more support from Germany.
For his part, Pope John Paul personified Polish resistance to Kremlin domination, and provided the spiritual force and legitimacy that underpinned Solidarity, the pro-democracy trade union that became a motor for change across the old eastern bloc. But Poland's church was not impregnable to its secret police. And while some heroes, like Fr Jerzy Popieluszko, resisted until communist agents killed them, other priests bent and snapped under the pressure.
Pope Benedict arrives in Poland amid revelations that another prominent priest spied for the communists, one of thousands who are now known to have done so, and his visit will perhaps bolster the confidence of a church that is facing its own demons. It is also a church that is deeply divided over Radio Maryja, a popular broadcaster that the Vatican has told to stop airing anti-Semitic and homophobic views and to stop acting as a cheerleader for Poland's deeply conservative new government.
While Benedict soothes Poland's historical wounds, he may feel the forces of tradition and change vying to shape its future.