Benedict also expressed sadness at the plight of divorced Roman Catholics who remarry without getting an annulment, reaffirming that they cannot receive Communion but stressing they should feel they still belong to the church.
The pope made the remarks to priests from the northern Valle d'Aosta region in a two-hour closed meeting Monday in Introd, near where he has been vacationing. The Vatican newspaper, L'Osservatore Romano, published a transcript of the remarks Wednesday.
The pope began his remarks, which touched on Marx, the upheavals in Europe of 1968 and other topics, by stressing that a pope isn't an "oracle" and "is infallible only in rare situations." Benedict previously has stressed that he intends to listen to others and not do only his will as pope.
He then delved into the issues raised by the Aosta bishop on the concerns of priests, noting that he was recently visited by bishops from Africa and Sri Lanka, where the number of priests is skyrocketing. In Europe and elsewhere, the number of priests has fallen sharply.
Benedict he said the "joy" at the growing numbers of churchmen in the developing world is accompanied by "a certain bitterness" because some would-be priests were only looking for a better life.
"Becoming a priest, they become almost like a head of a tribe, they are naturally privileged and have another type of life," he said. "So the wheat and the chaff go together in this beautiful growth of vocations.
"Bishops have to be very attentive to discern (among the candidates) and not just be happy to have many future priests, but to see which ones really are the true vocations - discern between the wheat and the chaff," he said.
Benedict also touched on another his favorite themes: the state of the church in Europe. He said in contrast to the developing world, where there is a "springtime of faith," the West was "a world that is tired of its own culture, a world that has arrived at a time in which there's no more evidence of the need for God, much less Christ, and in which it seems that man alone can make himself.
"This is certainly a suffering linked, I'd say, to our time, in which generally one sees that the great churches appear to be dying," he said, mentioning Australia, Europe and the United States.
Benedict also responded to a question about giving the Eucharist to divorcees who remarry without getting a church annulment. The church says divorcees who remarry civally cannot receive Communion, arguing they are in a state that "contrasts with God's law."
The pope reaffirmed the teaching, although he acknowledged the suffering it has caused and said further study is needed. He mentioned in particular the case of when someone gets married in a church without being a true believer, is divorced, remarries and discovers his or her faith, but isn't allowed to receive Communion.
In reaffirming the policy, he said the church had to respect "the good of the community and the good of the sacrament" as well as help those who are suffering. He said priests should teach that suffering is necessary "and this is a noble form of suffering."
Some Italian media reports have suggested the pope was reconsidering the ban, and that the issue would come up at a bishops' meeting in October dedicated to the Eucharist. The question has long been a concern for Benedict; in the 1990s, bishops from his native Germany asked for flexibility on the matter.
The 78-year-old Benedict marked his 100th full day as pope Thursday, a papacy already far longer than the 33-day term of John Paul I. Benedict's immediate predecessor, John Paul II, was pope for more than 26 years.