This week marks the second anniversary of Benedict XVI's papacy. Two years is but a blink of an eye in the history of this 2000 year-old institution. But it is enough to identify the particular lines being pursued by Catholicism's theologian-pope.
In one sense, the papacy's role is eternal, whoever occupies Peter's chair. It is to assist the Catholic Church in spreading the Christian message, to be the focus of unity for Catholics (particularly bishops) worldwide, and to explain and defend Catholicism's essential teachings.
For most people, that would seem more than enough to do. But each pope also brings specific issues to the position.
John Paul II, for example, became pope in 1978 with very clear ideas about the Church's relationship with the Communist world. To the entire Eastern Bloc, he began applying the same combination of prudence and moral toughness he had previously employed against Poland's Communists.
Given his age, Benedict knows he has limited time to pursue his particular concerns. The irony is that each amounts to a grand project in itself.
Unquestionably Europe - especially Western Europe - ranks high in Benedict's concerns. Even before becoming pope, Joseph Ratzinger had been writing about European cultural trends for decades.
Since his election, Benedict has repeated many times that Europe seems “tired,” and referenced its collapsing demography as symptomatic of deeper problems. But he upped the ante recently by insisting that the apparent determination of Europe's political classes to continue denying Europe's Judeo-Christian historical roots amounted to Europe apostatizing from itself.
Though few recognized it at the time, Benedict's now-famous 2006 Regensburg address also touched deeply on Europe.
This lecture - which will be remembered as one of this century's most provocative orations, akin to Aleksandr Solzhenitsyn's 1978 Harvard commencement address - identified the separation of faith and reason as central to the existential crisis of historical denial which Benedict believes is sapping Europe's civilizational genius.
It is not well understood that Benedict does not view this as an epic “Catholicism-versus-the Enlightenment” clash.
Careful reading of Benedict's speeches demonstrates his belief that many Enlightenment thinkers made positive contributions to Europe's development, especially with respect to religious liberty. Reason, Benedict writes, needs faith to check reason's potential for hubris, while faith needs reason to purify religion of unreasonable behavior.
Which brings us to another subject high on Benedict's agenda — Islam.
Catholicism and Islam are the world's fastest growing religions. They co-exist alongside and within each other. Significant Muslim minorities now live in Christianity's European hinterlands. Large numbers of Christians have lived in Islamic countries for centuries.
Early in his papacy, Benedict made clear his dissatisfaction with the character of official Catholic-Muslim dialogue. At Regensburg, he dramatically moved the conversation beyond the bromides all too common in ecumenical/inter-religious circles by publicly asking the question few had hitherto dared ask. Is violence somehow intrinsic to Islam, or is it an aberration?
The less-than coherent response from much of the Muslim world and many Westerners' evident unease that Benedict even posed the question indicates he struck a nerve, but also forced open a long overdue debate.
The stakes are not simply intellectual. Benedict was reminding Europe that the more it trivializes religion, the less it possesses the capacity to understand some of its own and Islam's problems. He was also attempting to facilitate a conversation about Islam and violence among Muslims themselves - an argument with profound implications for international stability.
The same debates also created room for Benedict to press another point that concerns him: the legal and informal restrictions endured by Christians living in Islamic countries. Benedict's 2006 visit to Turkey highlighted to the world the constraints upon the religious liberty of Christians living in this ostensibly secular Muslim country.
Benedict is not asking for some form of privileged status reminiscent of 19th century colonialism for Christians in Muslim countries. He is merely requesting reciprocity: that Christians in Muslim nations experience the same religious liberty enjoyed by Muslims living in nations with Christian heritages.
The same insistence upon religious liberty underpins Benedict's outreach to China, something no-one predicted as a priority for his papacy.
With millions of Chinese embracing Christianity as China opens economically to the world, Benedict believes the time is ripe for a Vatican-China rapprochement: one that respects China's sensitivities about sovereignty while ensuring Chinese Catholics can be in open communion with Rome. Progress is presently stalled. But a conversation considered inconceivable even five years ago continues.
In the midst of all this, Benedict continues to draw to St Peter's Square crowds larger than those who came to view his predecessor. By all accounts, many go less to see Benedict and more to listen to what he has to say.
Love or loathe him, it is difficult to ignore the elderly Bavarian scholar who speaks quietly but whose voice is a big stick.