Paris, France - Rule number one when Pope Benedict speaks: listen very carefully. Rule number two: be ready for surprises.
Joseph Ratzinger, who was a German university professor long before he became head of the Roman Catholic Church, is more seminar than soundbite when he speaks in public.
He can lecture as if only other philosophers and theologians were in the room, so listening hard or reading the text in full is essential. Even simple sermons can have an unexpected subliminal message.
Pope Benedict goes to the United States next week with a clear message of hope for its Catholics and appreciation for the role that faith and values play in American public life. The question papal experts ask now is how it will come across.
"He needs deciphering sometimes," said Thomas Noble, an historian of the papacy at the University of Notre Dame in Indiana. "He takes ideas very seriously and treats them at an elevated level."
In his three years as pope, the 80-year-old pontiff has displayed essentially three ways of communicating in public -- the complex speech, the simple homily and the surprise signal. All three are a challenge to today's soundbite culture.
THE COMPLEX SPEECH
Benedict is convinced that post-modern society -- especially in Europe -- is losing its moral compass by denying its roots in religion and embracing consumerism and individualism.
Just before his election in 2005, he highlighted this with a rare sound bite -- "the dictatorship of relativism ... whose ultimate goal consists solely of one's own ego and desires."
More typical was a 2004 debate about "the pre-political moral foundations of a liberal state" where his analysis was so convincing that his sparring partner -- the atheist German philosopher Juergen Habermas -- agreed with much of it.
But most readers would be lost in the jargon. "The ordinary person doesn't understand what relativism and post-modernism mean," said Georgetown University theologian Chester Gillis.
Benedict's 2006 Regensburg lecture was a learned discussion about faith, reason and ancient Greek philosophy. It contained a subtle call to Muslims to debate the role of reason in Islam.
Not easy to digest in any case, that message was drowned out when he quoted a Byzantine emperor saying Islam was violent and irrational. Violent protests broke out across the Muslim world and Benedict had to explain he did not agree with that view.
Benedict also met misunderstanding in his 2006 Auschwitz speech that developed the unusual argument that by killing Jews the Nazis ultimately wanted to destroy Christianity.
Jewish groups accused him of trying to "Christianize" the Holocaust and said he should have spoken instead more explicitly about German guilt and Christian anti-Semitism.
THE SIMPLE HOMILY
But Benedict can also deliver remarkably clear and effective sermons. Many get passed over by the secular media because they are mainly reflections on the day's scriptural readings.
"He's aware that, in the liturgy, you don't need to bring in heavy academic prose. You can speak simply and beautifully in a homily," said Monsignor Robert Batule, an American priest doing a comparative study of Benedict and the late Pope John Paul.
At the 2005 World Youth Day in Cologne, many young people there were not regular churchgoers and Benedict knew it. Instead of castigating them, though, he patiently sketched out his view of how Sunday Mass could help give meaning to their lives.
One year later in Regensburg, he dedicated a church organ with a short homily about how its pipes must all be in tune. Although he never mentioned Church dissidents, anyone listening to the Vatican's former doctrinal watchdog got the message.
Some of Benedict's most interesting comments are made off the cuff, in his native German or fluent Italian. A meeting with New York seminarians will show if he can do the same in English.
THE SURPRISING SIGNAL
Benedict's knack for sparking controversy often raises the question of whether some remarks, invariably delivered with a grandfatherly calm, are meant to shake up listeners as they do.
The controversial Regensburg speech clearly aimed to prompt a dialogue with Muslims. One has since started, even if the emperor's quote sowed misunderstanding and suspicion.
The pope surprised Muslims and some Catholics at Easter when he baptized a prominent Italian Muslim, Magdi Allam, in a gesture meant to stress the right to change religions. Again, an unresolved debate followed about whether that was appropriate.
"He never passes up an opportunity," Batule said. "He's not going to use occasions to throw bouquets but (to ensure) that key issues that need to be confronted actually get addressed.